Insights from Quasi-in situ Cryogenic-Transfer Atom Probe Tomography for Analyzing Hydrogen Diffusion in Metallic Alloys

Insights from Quasi-in situ Cryogenic-Transfer Atom Probe Tomography for Analyzing Hydrogen Diffusion in Metallic Alloys | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Insights from Quasi-in situ Cryogenic-Transfer Atom Probe Tomography for Analyzing Hydrogen Diffusion in Metallic Alloys Venkata Bhuvaneswari Vukkum, Zehao Li, Vaithiyalingam Shutthanandan, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5744208/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 09 Jul, 2025 Read the published version in npj Materials Degradation → Version 1 posted 11 You are reading this latest preprint version Abstract Cryogenic-transfer atom probe tomography (APT) has emerged as a powerful technique for nanoscale compositional analysis of hydrogen segregation in materials, offering critical insights into hydrogen embrittlement mechanisms. However, accurate quantification of hydrogen concentration in materials requires careful handling of sample exposure during the cryogenic transfer-APT process. Therefore, we describe the quantitative changes in the surface composition of hydrogen and oxygen in an austenitic FeCrNi model alloy during the ultrahigh vacuum transfer using the state-of-the-art LEAP 6000 XR APT, employing both deep UV laser-assisted and voltage pulsed modes of analysis. These insights were applied to interpret deuterium desorption from the FeCrNi alloy at room temperature after electrochemical deuterium-charging. The findings underscore the importance of managing sample exposure throughout the cryogenic-transfer APT process and introduce a novel quasi-in situ approach to analyzing hydrogen out-diffusion kinetics, which could be extended to a broader range of metallic alloys. Physical sciences/Materials science/Structural materials/Metals and alloys Physical sciences/Materials science/Materials for energy and catalysis Physical sciences/Materials science/Techniques and instrumentation Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Hydrogen is the lightest, smallest, and the most abundant element in nature. Hydrogen can diffuse into steel during manufacturing and service, leading to hydrogen embrittlement (HE) 1 , 2 . This has significant implications for fields such as nuclear fission/fusion reactors, and for the development of future clean energy technologies, where hydrogen interaction with materials plays a critical role 3 . The mechanistic interpretation of HE in iron alloys involves several theories, including hydrogen-enhanced decohesion (HEDE), hydrogen-enhanced local plasticity (HELP), adsorption-induced dislocation emission (AIDE), and hydrogen-enhanced strain-induced vacancies (HESIV) 3 , 4 . Experimental validation of these mechanisms requires spatially resolved mapping of hydrogen distribution in alloys at near-atomic resolution. Despite its importance, detecting and characterizing hydrogen at the nanoscale remains challenging 5 . Traditional methods, such as inert gas fusion (IGF) 6 , X-ray or neutron scatting or diffraction 7 , 8 and thermal desorption spectroscopy (TDS) 2 , 9 , have been widely used to quantify hydrogen content in various materials 1 , 3 , 10 . However, these bulk analysis methods are unable to provide spatially resolved nanoscale distribution of hydrogen within a material 1 . Only a limited number of advanced analytical techniques can map hydrogen distribution in materials at a nanoscale spatial resolution, like Time-of-flight secondary ion mass spectrometry (ToF-SIMS) 10 , Scanning Kelvin Probe microscopy 11 , 12 , scanning tunneling microscope 13 , 14 , and Atom probe tomography (APT) 15 . Among these methods, APT is the only technique that can provide three-dimensional compositional mapping of hydrogen distribution in materials at sub-nanometer scale spatial resolution 5 , 15 . In recent years, an increasing number of studies have used APT to detect hydrogen 2 , 16 , 17 , deuterium 4 , 18 – 20 , and hydrides 17 , 21 , 22 in iron 4 , 23 , 24 , Al 25 , 26 , Ti 17 , 27 , 28 and Zr 19 , 22 based alloys in which the hydrogen was introduced following direct ion implantation 29 , water corrosion 19 , gas charging 29 – 31 , electrochemical or cathodic charging 2 , 20 , 32 , 33 . Despite the increasing usage of APT for hydrogen detection, the analysis is subject to extreme sensitivity to experimental details like residual hydrogen gas concentration in the analysis chamber, hydrogen isotope loading method, pre- and post-loading and handling of the APT sample, and parameters followed during acquisition, making quantitative analysis of hydrogen distribution still challenging 5 . Several researchers 1 – 3 , 16 , 17 made significant progress toward analyzing hydrogen in materials using APT quantitatively or semi-quantitatively. Deuterium ( 2 H), an isotope of hydrogen with a larger atomic mass (2 Da) while exhibiting similar chemical reactivity, is often employed as a substitute for hydrogen in APT studies. This approach helps to mitigate the convolution between hydrogen that is intentionally charged into materials from the hydrogen already within the material and from the residual hydrogen signal from H in the APT analysis chamber 5 . Meier et al. 16 compared the voltage pulsed vs. pulsed UV laser APT in deuterium-charged and uncharged materials. While voltage-pulsing only yielded a clear 2 H-peak (at 2 Da) for deuterium (denoted as D from here on) charged specimens, both D-charged and uncharged samples produced significant peaks at 2 Da in laser-pulsing APT, complicating peak assignment. Therefore, voltage-pulsing APT is often recommended for hydrogen analysis of conductive materials to achieve better analytical yields and improved quantification. Chen et al. 33 compared H/D electrochemical charging using electrolytes with different combinations of H 2 O, D 2 O, NaOH, and NaOD and demonstrated that D 2 O, combined with either NaOD or NaOH electrolytes, is equally effective in introducing deuterium into steel specimens, which can be followed by voltage-pulsing based APT analysis. Atom probe tomography (APT) with cryogenic sample transfer capability is being increasingly used for quantitative analysis of hydrogen in metals as it can prevent the hydrogen out diffusion from metals with high H diffusivities 1 , 2 , 4 , 5 , 25 , 34 – 37 . This transfer capability employs an ultra-high vacuum cryogenic transfer shuttle (UHVCTS) suitcase that prevents the APT needle from exposure to the external environment and helps connect and transfer the APT needles between FIB, APT, and Glovebox. Researchers 25 , 34 – 37 reported cryogenic sample transfer capability using UHVCTS as an effective method for studying materials that are sensitive to the environment, which includes magnesium 36 , 38 , aluminum 25 , and iron alloys 2 , 4 . In addition, the use of cryogenic FIB milling and transfer has proven to be beneficial to minimize hydrogen uptake and hydride formation during sample preparation 39 . In steel, Chen et al. 20 employed cathodic or electrolytic charging followed by cryogenic transfer-APT to analyze hydrogen trapping in carbides, such as V-Mo-C and NbC, which revealed different H trapping mechanisms depending on carbide stoichiometry. In their follow-up study, Chen et al. 40 further identified that H trapping can occur both at interfaces and in carbon vacancies in the carbide bulk. Zhao et al. 26 used cryogenic transfer-APT to map H-trapping sites at grain boundaries and precipitates of aluminum alloys, contributing to a better understanding of hydrogen embrittlement in metals. More recently, Dallin et al. 4 compared the deuterium pick up in pure iron (ferrite) and austenitic FeCrNi alloy after electrochemical charging followed by transfer to APT performed either at room temperature or after cryogenic-plunging prior to APT analysis, revealing that cryogenic plunge freezing and transfer prevented the deuterium out-diffusion from samples. These past studies underscored the critical role of ultra-high vacuum and cryogenic temperature handling in preventing hydrogen or deuterium loss during sample preparation and transfer to APT. However, all the aforementioned literature discussion on the cryogenic sample transfer approach predominantly used the CAMEA LEAP 3000 2,20 , 4000 4,20,25,39,40 , and 5000 2,26,36,37 atom probe tomography systems. The LEAP 6000 XR is the latest generation of APT with deep UV laser (257.5 nm wavelength) and 52% detection efficiency (DE) compared to 3000 HR (green laser with 532 nm wavelength, 37% DE), 4000 XR (UV laser with 355 nm wavelength, 37% DE) and 5000 XR (UV laser with 355 nm wavelength, ~ 50% DE) 41 . Given that the LEAP 6000 XR is the latest APT model, very limited studies 42 , 43 have used LEAP 6000 XR APT for material characterization so far. Notably, no studies have been reported on hydrogen detection following cryogenic-transfer workflow into a LEAP 6000 XR so far. Therefore, we hereby focus on providing the first results from cryogenic-transfer APT utilizing a LEAP 6000 XR APT. Moreover, studies to date, in analyzing hydrogen isotope diffusion within materials using cryogenic transfer-APT has predominantly focused on examining hydrogen-charged materials immediately after cryogenic transfer 1 , 2 , 4 , 5 , 20 , 26 , 30 , 42 . Interestingly, to the best of our knowledge, no efforts have been made to investigate hydrogen out-diffusion from cryogenically transferred, hydrogen-charged samples as they are warmed up to different time periods. Given that APT analysis can be paused, allowing the sample to warm to room temperature within the APT buffer chamber vacuum before resuming analysis, this presents a quasi-in situ approach to study hydrogen out-diffusion from materials. Such an approach enables the analysis without significantly altering the surface of the APT needles. However, this method remains unexplored in the literature. In this work, we test the feasibility and address the challenges of analyzing hydrogen out-diffusion from materials using this quasi-in situ approach. Results and Discussion Cryogenic transfer procedure between PFIB, APT, and N 2 -Glovebox using UHVCTS The experimental setup, including the plasma-focused ion beam (PFIB), APT, Ferrovac extension kit connected to an N₂-glovebox, and the UHVCTS used for shuttling Fe18Cr14Ni alloy needles between systems are given in Fig. 1 (a). The FeCrNi model alloy needle, with an apex diameter of 40–100 nm, was prepared via electropolishing followed by annular milling in PFIB. The prepared needle can be seamlessly transferred between the APT, PFIB, and N 2 -glovebox using the UHVCTS, with each system equipped with dedicated docking stations for the UHVCTS suitcase, as shown in Fig. 1 a. The electrochemical deuterium charging experiment is conducted inside the N 2 -glovebox. Detailed photographs of individual instrumentation and parts of the cryogenic transfer-APT workflow are presented in Fig. 1 (b-j). The Ferrovac extension kit allows seamless integration between the UHVCTS and the N 2 glovebox (Fig. 1 b). A cryogenic load lock with a vertical receptacle elevator allows the transfer of an APT sample puck into and out of the LN 2 basin situated within the N2 glove box (Figs. 1 c-d). The supporting tool and guide rail within the LN 2 basin facilitate the manual removal of the APT puck with the pre-loaded needle sample and load it to the receptacle base (Figs. 1 (d-f)). For electrochemical charging, the APT needle sample pre-loaded in the APT puck is oriented upside down using a puck manipulator located inside the glove box, allowing only the apex of the sample to be immersed in a 0.1 M NaOD electrolyte with 8 g/L thiourea for deuterium electrochemical charging at -2.2 V (vs. Ag/AgCl) for 300 seconds, as shown in Fig. 1 g. During D-charging, the LN 2 basin was filled with liquid nitrogen (Fig. 1 b), for cooling the receptacle base and supporting tool. Following D-charging, the APT puck with the needle sample was placed onto the LN 2 -cooled receptacle base within 30 seconds of stopping the power supply, transferred back to the cryogenic load lock, and moved to the UHVCTS. It was subsequently transferred to the 360 o rotation cryogenic stage installed within the PFIB for annular milling (Fig. 1 h). The final needle sample was then transferred from PFIB to APT using UHVCTS. The LN 2 dewar attached to the UHVCTS maintained the needle at cryogenic temperatures during the transfer, as shown in Fig. 1 i. The piggyback puck, pre-cooled in the analysis chamber (Fig. 1 j), ensures the needle remains at cryogenic temperatures while being transported from the APT load lock to the analysis chamber for the APT analysis conducted in voltage or laser pulsing modes. Quantifying the hydrogen and oxygen pickup in FeCrNi alloys during the cryogenic transfer process First, we aimed to quantify the hydrogen (H) and oxygen (O) pickup on FeCrNi needle samples during the transfer process between the APT buffer chamber and N 2 -glovebox under laser and voltage pulsing modes, as presented in Fig. 2 a. The FeCrNi needle was prepared via electropolishing, followed by annular milling in PFIB. The prepared needle was first transferred to the APT using the UHVCTS for collecting a baseline data, first in voltage and then in laser pulsing modes, collecting 1 million ions in each analysis. Subsequently, the APT analysis was interrupted, and the needle sample was taken out of the analysis chamber and was transferred to the N 2 -glovebox using the UHVCTS and held in the glove box for 30 minutes before transferring it back into the APT analysis chamber and conducting laser and then voltage pulsing mode APT analysis. An additional dataset of 0.5 million ions was acquired for each APT analysis to quantify the O and H pickup that occurred cumulatively due to the 30-minute glove box exposure and the transfer process to and from the glove box. After that, the APT analysis was again interrupted, and the same needle sample was allowed to warm up to room temperature in the APT buffer chamber (maintained between 1.6E-8 to 1.2E-8 torr) for 30 minutes, followed by transferring the sample back into the APT analysis chamber. The buffer chamber vacuum recorded during the 30 minutes hold in buffer chamber is presented in Supplementary Fig. 1. The sample was re-analyzed first in laser pulsing mode and then in voltage pulsing mode immediately after, and an additional dataset of 0.7 million ions each was collected to assess how much O and H pickup occurred in the sample during the 30-minute exposure to the buffer chamber vacuum and how the laser vs voltage mode influences the compositional quantification of H and O under the same conditions. The mass-to-charge spectra from the APT dataset collected in laser pulsing mode for baseline, buffer chamber (30 min), and glovebox (30 min) conditions are shown in Figs. 2 (b-d). The Laser pulsed mode mass-to-charge spectra for all conditions exhibited similar peaks for H, H 2 , C, and O in the + 1 charge state and C, Fe, Cr, and Ni in the + 2 charge state, and Fe, Cr, and Ni peaks in the + 1 charge state for all conditions, as indexed in Fig. 2 (b-d). Moreover, oxide molecular peaks of Fe, Cr, and Ni in both + 1 and + 2 charge states were observed across all conditions in laser pulsing mode (Fig. 2 c and 2 d). For all compositional analysis, overlapping peaks for Cr + 2 /Fe + 2 (at 27 Da), Fe + 2 /Ni + 2 (at 29 Da), Ni + 2 /O 2 + 2 (at 32 Da), Fe + 1 /Cr + 1 (at 54 Da), and Fe + 1 /Ni + 1 (at 58 Da) was deconvoluted using non-overlapping isotopic peaks. A 10 nm diameter cylinder was used to quantify the 1D composition profile of the baseline APT data reconstruction where the cylinder region of interest was specifically placed well below the top surface of the reconstruction to avoid the PFIB damage layer. This allowed us to quantify the composition of the needle surface at the end of the baseline clean up APT analysis before it was exposed to buffer chamber or glove box environments. In the case of the APT reconstructions after 30 min exposure in buffer and glove box, the 10nm cylinder ROI was placed to quantify the composition change right from the top surface of those reconstructions. The 1D concentration profiles of Fe, Cr, Ni, O, H, C, and N for laser pulsing mode datasets are provided in Supplementary Fig. 2. The hydrogen composition profiles of baseline, 30-minute buffer chamber, and 30-minute glovebox conditions in laser pulsed mode are presented in Fig. 2 e. The hydrogen detected in the baseline clean-up APT analysis condition may result from the hydrogen introduced to the sample during the electropolishing and PFIB annular milling or from the desorption of absorbed hydrogen from the APT analysis chamber. After 30 min exposure of the same sample to the buffer chamber or glove box environment, the hydrogen concentrations within the top 0.6 nm near the top surface of the reconstructions increased considerably compared to the end of baseline APT analysis (Fig. 2 e). Additionally, from the oxygen 1D composition profiles in each of those conditions from the laser-pulsed mode datasets (given in Fig. 2 f) it is clear that oxygen concentrations within the top 0.7 nm near the surface of the reconstructions increased compared to the baseline after 30 min exposure in the buffer chamber and glove box, suggesting near-surface oxidation of the needle samples even during the exposure to the buffer chamber vacuum and glove box environment and during the UHVCTS transfer. The bulk hydrogen concentration quantified from the entire reconstructions after 30 min exposure in the buffer chamber and glove box clearly showed an increase when compared with the H-concentration in the baseline APT data (Fig. 2 g). As described above, after 30 min exposure to the buffer chamber and to glove box environments, first, a laser pulsed mode APT analysis was conducted. Each of those laser-pulsed APT analyses was interrupted after collecting at least 0.5 million ions, and a voltage-pulsed APT analysis was conducted immediately after to quantify the change between laser and voltage modes of analysis. The mass-to-charge spectra from the APT dataset collected in back-to-back voltage pulsing modes for baseline, buffer chamber (30 min), and glovebox (30 min) conditions are shown in Figs. 3 (a-b). The voltage-pulsed mode mass-to-charge spectra for all conditions exhibited similar peaks for H, C, and O in the + 1 charge state and C, Fe, Cr, and Ni in the + 2 charge state, as indexed in Fig. 3 b. Only for the APT reconstruction of the baseline cleanup step, xenon (Xe) peaks were observed at 64–68 Da, resulting from Xe beam damage during PFIB sample preparation (Fig. 3 a). The 1D concentration profiles of Fe, Cr, Ni, O, H, C, and N for the voltage pulsing mode datasets are provided in Supplementary Fig. 3. The 1D composition profile of H in the three back-to-back voltage analyses given in Fig. 3 c still showed an increased H concentration within the top 0.3 nm of the reconstructions after exposure to the buffer chamber and glove box. Essentially, the H concentration measured at the end of the laser pulsed analysis and the back-to-back voltage analysis for each of these conditions appeared to differ. The oxygen 1D concentration profiles from the back-to-back voltage analysis show no apparent surface oxidation, which can be expected since the top oxidized surface of needle samples were already analyzed in the laser mode before (Fig. 3 d). Moreover, like the observations in the laser mode datasets, in the back-to-back voltage mode datasets also there was clear evidence for increased bulk H concentration in the samples after exposure to the glove box and buffer chamber vacuum for 30 mins (Fig. 3 e). However, the quantified amount of hydrogen was substantially lower in the case of voltage mode datasets versus laser mode dataset for the same needle sample for the baseline and 30 min exposed conditions. Meir et. al and other authors showed the pulsed laser mode led to the H 2 peak at 2Da in the case of UV laser 1 , 5 , 16 . This observation appears to remain consistent in the case of the deep UV laser used in the LEAP 6000 XR, and therefore possibly directly contributing to an over-estimation of the hydrogen concentration when analyzed in pulsed laser mode. Also given the peak at 2Da will overlap with the deuterium peak, for the electrochemical deuterium charging experiments in workflow 2, we only used voltage mode of analysis. This detailed understanding of the changes to the near-surface H and O concentration of APT needle samples during the transfer process to APT buffer chamber and glove box allows us to better understand the changes in the composition of deuterium-charged samples measured before and after cryogenic transfer APT, which is described next. Quantification of deuterium pickup and desorption kinetics from the electrochemical deuterium charged FeCrNi model alloy The quantification of deuterium pickup after electrochemical deuterium charging in the N 2 -glovebox and deuterium desorption kinetics after sequential warm-up inside the APT buffer chamber is investigated in the second workflow, as presented in Fig. 4 a. Initially, a second needle of FeCrNi alloy is prepared via electropolishing, followed by PFIB annual milling. The PFIB-prepared FeCrNi needle was initially transferred to the APT via the UHVCTS for baseline measurements in voltage pulsing mode (Fig. 1 a). After collecting the baseline APT data, the needle was transferred to the glovebox via the UHVCTS, facilitated by the Ferrovac extension kit for the D-charging experiment (at -2.2 V (vs. Ag/AgCl) for 300 seconds in 0.1 M NaOD electrolyte with 8 g/L thiourea as a recombination poison). Post-charging, the needle was immediately plunged in LN 2 , frozen, and transferred to PFIB for annular milling and then to APT using the Ferrovac extension kit and UHVCTS and analyzed in voltage-pulsed mode to quantify the deuterium pickup. After collecting at least 1 million ions, the APT experiment was interrupted and the needle sample was taken out of the APT analysis chamber and then placed in the APT buffer chamber carousel at room temperature and held for 30 minutes, followed by voltage pulsing APT analysis. The APT analysis was again interrupted after collecting 1 million ions and then transferred back to the buffer chamber and held for an additional 90 minutes at room temperature and transferred back into the analysis chamber and analyzed again in voltage pulsed mode. During the warm-up, the buffer chamber vacuum fluctuations were recorded and presented in Supplementary Fig. 4. The buffer chamber vacuum fluctuated between 4E-8 and 1E-7 Torr during the 30-minute hold and between 3.5E-8 and 4.5E-7 Torr during the 90-minute hold. This 30-minute and 90-minute warm-up of the deuterium-charged sample in the buffer chamber, followed by APT analysis, was conducted to analyze the deuterium out-diffusion from the sample at room temperature. The APT mass-to-charge spectra of baseline, deuterium charged, and after 30 min and 90 min warm up in buffer chamber exhibited similar peaks for H, O, N, Fe, Ni in + 1 charge state and C, Fe, Cr, and Ni in + 2 charge state (Fig. 4 b). Additionally, the oxide molecular peaks of Fe, Cr, and Ni in + 1 and + 2 charge states are observed in all four conditions. The oxide molecular peaks were most predominant in D-charged conditions. The carbon peaks at 6 and 12 Da were observed only initially in the baseline cleanup APT reconstruction, which could be minor surface contamination. The deuterium peak at 2 Da was observed in D-charged, buffer chamber 30 min and 90 min conditions. Like the data analysis for workflow 1, a 10 nm diameter cylinder was used to quantify the 1D composition profile of the baseline clean-up APT reconstruction where the cylinder region of interest was specifically placed well below the top surface of the reconstruction to avoid the PFIB damage layer. This allowed us to quantify the composition of the needle surface at the end of the baseline clean-up APT analysis before it was electrochemically charged with deuterium. In the case of the APT reconstructions, after deuterium charging and warm-up for 30 min and 90 min in the buffer chamber, the 10nm cylinder ROI was placed to facilitate the quantification of the composition change right from the top surface of those reconstructions. The 1D concentration profiles of Fe, Cr, Ni, O, H, C, and N for the baseline, D-charged, 30-minute, and 90-minute warmed samples in the buffer chamber are provided in Supplementary Fig. 5. The overlay of 1D composition profiles of H, D, and O in the baseline, D-charged, 30-min, and 90-min warmed samples in the buffer chamber are given in Figs. 4 c, d, and e, respectively. At the end of the baseline condition, the H, D, and O concentrations were notably low. However, after the electrochemical deuterium charging and cryogenic transfer of FeCrNi samples from the N2-glove box to PFIB and then to LEAP 6000XR using UHVCTS resulted in a significant increase in the near-surface concentrations of H and O, which interestingly coincided with a near-surface depletion of D. But the D concentration deeper in the needle was highest after the electrochemical charging and cryogenic transfer. The bulk D concentration is quantified and plotted in Fig. 4 f, along with corresponding ion maps in Fig. 4 g. From Fig. 4 f, it is evident that the overall bulk concentration of Deuterium quantified in the reconstruction of the D-charged sample reduced in subsequent reconstructions after warm-up for 30 min and 90 min in the buffer chamber vacuum. Following D-charging, the bulk D concentration peaked at ~ 1.4 at. % and gradually declined to ~ 1.1 at. % after 30 minutes and ~ 0.7 at. % after 90 minutes of warming at room temperature in the buffer chamber vacuum, signifying the D out-diffusion from the sample. Interestingly, following the 90-minute warmup in buffer chamber, although the bulk deuterium concentration decreased, the local deuterium concentration near to top surface of reconstruction within ~ 1 nm depth increased to ~ 7 at. %. It is plausible that during the 90-minute warmup in the buffer chamber, a continuous thin surface oxide layer formed on the needle surface, which likely acted as a diffusion barrier leading to a near-surface accumulation of deuterium. These findings underscore the dynamic desorption behavior of deuterium and the interactions between hydrogen, oxygen, and the FeCrNi needle sample after deuterium charging and during warm-up to room temperature in the buffer chamber environment. Conclusions In summary, we first analyzed the nanoscale compositional changes near the top surface of an austenitic Fe18Cr14Ni alloy needle sample during the cryogenic transfer process and on prolonged exposure to the buffer chamber vacuum at room temperature. To achieve this, we did a series of experiments using laser and voltage modes on the same FeCrNi alloy needle sample. This allowed us to make quantitative comparisons of hydrogen and oxygen compositions across different exposure conditions of the sample. The needle sample was first analyzed in voltage and laser mode to obtain a quantitative analysis of H and O within the sample initially. Subsequent exposure of the same needle sample in the buffer chamber vacuum for 30 min revealed surface oxidation and hydrogen absorption. The same sample was also transferred to the glove box using UHVCTS, then held in the glovebox for 30 minutes and transferred back into APT, which led to a higher extent of oxidation and H-ingress. The comparison of back-to-back laser pulsed and voltage pulsed analysis revealed that laser-pulsing tends to overestimate the Hydrogen concentration in the samples, and the H 2 peak appeared at 2Da even with the deep UV laser used in LEAP 6000 XR. This understanding of the influence of sample exposure during the transfer process was then used to better interpret the results of a second needle sample that was deuterium-charged electrochemically and cryogenically transferred to PFIB and then to APT using UHVCTS. In addition, subsequent measurement of changes in Deuterium, Hydrogen, and oxygen concentrations in the same needle due to 30 min and 90 min warm up to room temperature within the buffer chamber aided in analyzing the deuterium-desorption kinetics from the deuterium-charged FeCrNi alloy sample. The deuterium concentration in the sample progressively reduced during the warmup time in the buffer chamber, which points to the possibility of using such a quasi-in situ approach to analyze hydrogen isotope desorption from a wide class of materials. Presumably maintaining the buffer chamber vacuum to levels below the 5E-8 torr could further reduce surface oxidation during the controlled warm up of samples and that could improve the quantification of deuterium out-diffusion by avoiding the formation of a surface oxide layer altogether. The findings from this work provide a precise measure of the factors to be considered during the cryogenic transfer APT experiments and its potential to achieve a nanoscale understanding of hydrogen diffusion kinetics within metal alloys, which could be applied to a broad class of metal alloys. We anticipate this approach to be particularly suitable for analyzing the influence of specific defects and alloy chemistry changes for modifying the hydrogen diffusion kinetics in materials, which could be invaluable both for better understanding hydrogen embrittlement mechanisms and for hydrogen storage material development efforts. Experimental Fe18Cr14Ni alloy was fabricated by induction melting high-purity elements, followed by casting and homogenizing through five remelting cycles. These alloys were subsequently cold rolled to reduce their area by 50% and recrystallized into 3 mm thick sheets by annealing at 900 ℃ for 4 hours. Using electric discharge machining, bars with a 1 mm² cross-section were cut from the fabricated Fe18Cr14Ni alloy. These bars were ground and polished on all sides, progressively using finer grits to a 1 mm diamond suspension. The prepared 1 mm² bars were sharpened into needles using a two-step polishing procedure. Initially, coarse polishing was performed with a 25% perchloric acid solution in glacial acetic acid. This was followed by fine polishing using a 2% perchloric acid solution in 2-butoxyethanol. Thermo Fisher Helios Hydra plasma-focused ion beam (FIB) with Xe plasma was used to final polish the needles to 40–80 nm apex diameter following the annular milling process. The ion milling process was carried out at a voltage of 30 kV, gradually decreasing the current, with the final milling step performed at 2 kV and 10 pA. Atom probe tomography (APT) was conducted using a CAMECA local electrode atom probe (LEAP) 6000 XR, operating in voltage pulsing mode with a 20% pulse fraction and laser mode with 25pJ laser pulse energy while maintaining 200KHz pulse frequency and 0.5% Detection rate. The sample temperature was maintained at 50K for all APT data collection in workflow 1. The collected APT data was reconstructed and analyzed using Interactive Visualization and Analysis Software (IVAS). The ultra-high vacuum cryo transfer shuttle (UHVCTS) suitcase was used to transfer samples between plasma-focused ion beam (PFIB), APT, and N 2 -glovebox. In workflow 2, the deuterium desorption experiments were conducted by warming the samples within the buffer chamber for 30 and 90 minutes and followed by APT data collection in voltage pulsing mode. For the APT experiments of Deuterium charged samples, the sample temperature was maintained at 70K. During the warm-up, the buffer chamber vacuum fluctuated between 5E-8 Torr and 4E-7 Torr. Electrochemical experiments were carried out using an Ossila potentiostat with a FIB-prepared FeCrNi needle acting as the working electrode (WE), Ag/AgCl (0.1 M KCl) as the reference electrode (RE), and Pt wire as the counter electrode (CE). The FIB-prepared FeCrNi needles were subjected to -2.2 V Ag/AgCl constant voltage for 300 seconds in 0.1 M NaOD with 8g/L Thiourea electrolytes for deuterium electrochemical charging. Prior to the electrochemical experiments, the open circuit potentials were recorded while the specimen was stabilized in the test electrolyte for 100 seconds. All the electrochemical experiments were conducted inside the N 2 glovebox while maintaining < 1 ppm oxygen and < 10 ppm moisture. Declarations Competing Interest The authors declare no competing interests. Author Contribution V.B.V. performed the experiments, including electropolishing, FIB, APT, electrochemical charging, and APT data analysis. Z.L. contributed to FIB and APT experiments. V.S. and V.B.V. led the installation of the glovebox and Ferrovac extension kit. A.D. procured the funding and conceptualized the project and guided the APT data analysis and supervised the entire project. The original manuscript was drafted by V.B.V. and reviewed and revised by all authors. Acknowledgement This research was supported by the Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences, and Engineering Division as a part of the Early Career Research Program FWP 76052. V.B. acknowledges Jack Grimm for the discussions related to APT and support in APT data reconstruction. V.B. acknowledges Mengkong (Andrew) Tong for the electrochemical charging assembly fixture development. Data Availability The data can be made available upon reasonable request. References Chen, Y.-S. et al. Atom Probe Tomography for the Observation of Hydrogen in Materials: A Review. Microscopy and Microanalysis 29 , 1-15 (2023). https://doi.org/10.1093/micmic/ozac005 Breen, A. J. et al. Solute hydrogen and deuterium observed at the near atomic scale in high-strength steel. Acta Mater 188 , 108-120 (2020). https://doi.org/10.1016/j.actamat.2020.02.004 Chen, Y.-S. et al. Hydrogen trapping and embrittlement in metals – A review. 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Characterizing solute hydrogen and hydrides in pure and alloyed titanium at the atomic scale. Acta Mater 150 , 273-280 (2018). https://doi.org/10.1016/j.actamat.2018.02.064 Kesten, P. et al. H- and D distribution in metallic multilayers studied by 3-dimensional atom probe analysis and secondary ion mass spectrometry. J Alloy Compd 330 , 225-228 (2002). https://doi.org/Doi 10.1016/S0925-8388(01)01596-1 Sundell, G., Thuvander, M., Yatim, A. K., Nordin, H. & Andrén, H. O. Direct observation of hydrogen and deuterium in oxide grain boundaries in corroded Zirconium alloys. Corrosion Science 90 , 1-4 (2015). https://doi.org/10.1016/j.corsci.2014.10.016 Chen, Y. S. et al. Direct observation of individual hydrogen atoms at trapping sites in a ferritic steel. Science 355 , 1196-1199 (2017). https://doi.org/10.1126/science.aal2418 Takahashi, J., Kawakami, K., Otsuka, H. & Fujii, H. Atom probe analysis of titanium hydride precipitates. Ultramicroscopy 109 , 568-573 (2009). https://doi.org/10.1016/j.ultramic.2008.11.012 Hudson, D., Cerezo, A. & Smith, G. D. W. Zirconium oxidation on the atomic scale. Ultramicroscopy 109 , 667-671 (2009). https://doi.org/10.1016/j.ultramic.2008.10.020 Takahashi, J., Kawakami, K. & Kobayashi, Y. Origin of hydrogen trapping site in vanadium carbide precipitation strengthening steel. Acta Mater 153 (2018/07/01). https://doi.org/10.1016/j.actamat.2018.05.003 Takahashi, J., Kawakami, K., Kobayashi, Y. & Tarui, T. The first direct observation of hydrogen trapping sites in TiC precipitation-hardening steel through atom probe tomography. Scripta Materialia 63 (2010/08/01). https://doi.org/10.1016/j.scriptamat.2010.03.012 Macauley, C., Heller, M., Rausch, A., Kummel, F. & Felfer, P. A versatile cryo-transfer system, connecting cryogenic focused ion beam sample preparation to atom probe microscopy. PLoS One 16 , e0245555 (2021). https://doi.org/10.1371/journal.pone.0245555 Zhao, H. et al. Hydrogen trapping and embrittlement in high-strength Al alloys. Nature 602 , 437-+ (2022). https://doi.org/10.1038/s41586-021-04343-z Chang, Y. H. et al. Ti and its alloys as examples of cryogenic focused ion beam milling of environmentally-sensitive materials. Nat Commun 10 (2019). https://doi.org/ARTN 94210.1038/s41467-019-08752-7 Chang, Y. H. et al. Quantification of solute deuterium in titanium deuteride by atom probe tomography with both laser pulsing and high-voltage pulsing: influence of the surface electric field. New J Phys 21 (2019). https://doi.org/ARTN 05302510.1088/1367-2630/ab1c3b Takamizawa, H. et al. Three-Dimensional Characterization of Deuterium Implanted in Silicon Using Atom Probe Tomography. Appl Phys Express 6 (2013). https://doi.org/Artn 06660210.7567/Apex.6.066602 Khanchandani, H. et al. Laser-equipped gas reaction chamber for probing environmentally sensitive materials at near atomic scale. Plos One 17 (2022). https://doi.org/ARTN e026254310.1371/journal.pone.0262543 Takahashi, J., Kawakami, K., Sakiyama, Y. & Ohmura, T. Atomic-scale observation of hydrogen trap sites in bainite-austenite dual-phase steel by APT. Mater Charact 178 (2021). https://doi.org/ARTN 11128210.1016/j.matchar.2021.111282 Ozdirik, B. et al. Development of an Electrochemical Procedure for Monitoring Hydrogen Sorption/Desorption in Steel. Journal of the Electrochemical Society 164 , C747-C757 (2017). https://doi.org/10.1149/2.0521713jes Chen, Y. S., Bagot, P. A. J., Moody, M. P. & Haley, D. Observing hydrogen in steel using cryogenic atom probe tomography: A simplified approach. International Journal of Hydrogen Energy 44 , 32280-32291 (2019). https://doi.org/10.1016/j.ijhydene.2019.09.232 Chen, Y.-S., Griffith, M. J. & Cairney, J. M. Cryo Atom Probe: Freezing atoms in place for 3D mapping. Nano Today 37 (2021). https://doi.org/10.1016/j.nantod.2021.101107 McCarroll, I. E., Bagot, P. A. J., Devaraj, A., Perea, D. E. & Cairney, J. M. New frontiers in atom probe tomography: a review of research enabled by cryo and/or vacuum transfer systems. Mater Today Adv 7 (2020). https://doi.org/10.1016/j.mtadv.2020.100090 Stephenson, L. T. et al. The Laplace Project: An integrated suite for preparing and transferring atom probe samples under cryogenic and UHV conditions. PLoS One 13 , e0209211 (2018). https://doi.org/10.1371/journal.pone.0209211 Woods, E. V. et al. A Versatile and Reproducible Cryo-sample Preparation Methodology for Atom Probe Studies. Microsc Microanal 29 , 1992-2003 (2023). https://doi.org/10.1093/micmic/ozad120 Schwarz, T. M. et al. Quasi‐“In Situ” Analysis of the Reactive Liquid‐Solid Interface during Magnesium Corrosion Using Cryo‐Atom Probe Tomography. Advanced Materials 36 (2024/08/01). https://doi.org/10.1002/adma.202401735 Zhou, Z. et al. Cryogenic atom probe tomography and its applications: a review. Microstructures 3 (2023). https://doi.org/10.20517/microstructures.2023.38 Chen, Y. S. et al. Observation of hydrogen trapping at dislocations, grain boundaries, and precipitates. Science 367 , 171-+ (2020). https://doi.org/10.1126/science.aaz0122 Jakob, S. & Thuvander, M. Revisiting Compositional Accuracy of Carbides Using a Decreased Detector Efficiency in a LEAP 6000 XR Atom Probe Instrument. Microscopy and Microanalysis (2024). https://doi.org/10.1093/mam/ozae069 Jakob, S., Sattari, M., Sefer, B., Ooi, S. & Thuvander, M. Characterization of hydrogen traps in a co-precipitation steel investigated by atom probe experiments without cryogenic transfer. Scripta Materialia 243 (2024/04/01). https://doi.org/10.1016/j.scriptamat.2023.115963 Jakob, S., Thuvander, M. & Ooi, S. W. Comparison of Hydrogen Resilience of Three Different Corrosion-Resistant Martensitic Steels. https://doi.org/10.2139/ssrn.5028452 Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5744208","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":398907164,"identity":"66b7768b-d099-4c5e-913b-39ab0aebd142","order_by":0,"name":"Venkata Bhuvaneswari Vukkum","email":"","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Venkata","middleName":"Bhuvaneswari","lastName":"Vukkum","suffix":""},{"id":398907165,"identity":"a385892e-e14f-43b0-a2d9-440b263e4b72","order_by":1,"name":"Zehao Li","email":"","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Zehao","middleName":"","lastName":"Li","suffix":""},{"id":398907166,"identity":"8f20b423-a5b2-413e-a092-691d6b9f1ac1","order_by":2,"name":"Vaithiyalingam Shutthanandan","email":"","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Vaithiyalingam","middleName":"","lastName":"Shutthanandan","suffix":""},{"id":398907167,"identity":"8190ce50-ddb6-4168-b9b4-0d314d530429","order_by":3,"name":"Arun Devaraj","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5klEQVRIie3RMYvCMBTA8VcCyRJ0zS31K7wSUA5OP4tF6KQiFDo79abDteD3EEeh4PQo3H5DDsG5q5NWK7rFugnmPyRvyG8ID8Dletl4fWFZHa2nSJDd54aEySakvaSugeQrXCxzE/fXf1MO4ncnLUQV4x5CEYVZEaGe0D7mIGNtI0Cyq7w010BQkTQPU5DRR2YRnZocdYdEqT+bEKzJxq8G1N6FiK0qLSQgnqhhMfIDkrPghyrCJEMb8YmtVJkMpE9ihYd1Hi7E978Z2r5/7vqAozeH83bwEbjFzIWAMI2Jy+VyvUUnIjxGVbBaafMAAAAASUVORK5CYII=","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":true,"prefix":"","firstName":"Arun","middleName":"","lastName":"Devaraj","suffix":""}],"badges":[],"createdAt":"2025-01-01 02:23:06","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5744208/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5744208/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41529-025-00626-2","type":"published","date":"2025-07-09T15:57:44+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":73236247,"identity":"ca516b9d-8dfb-4a43-99ce-499a6a9ded9b","added_by":"auto","created_at":"2025-01-08 05:02:45","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":2363438,"visible":true,"origin":"","legend":"\u003cp\u003e(a) the overview of the cryogenic transfer-APT system and components including an optical image of the electropolished FeCrNi needle sample, photographs of the PFIB, a LEAP 6000 XR APT with an ultra-high vacuum cryogenic transfer suitcase (UHVCTS), and N\u003csub\u003e2\u003c/sub\u003e-glovebox with Ferrovac extension kit and schematic of D-charging set up. Detailed photographs of individual parts of the cryogenic transfer system b) Ferrovac extension kit connected to N2-glovebox c) the cryogenic load lock inside the glove box with a receptacle elevator d) the receptacle base and support tool used to load APT samples into the receptacle elevator e) an APT sample puck with an FeCrNi needle sample sitting on the receptacle base f) the puck manipulator used to transfer the APT puck with pre-loaded electropolished FeCrNi wire to the electrochemical charging station inside the N2 glovebox g) The electrochemical charging set up with inverted APT puck as working electrode as well as Pt counter electrode (CE) and Ag/AgCl reference electrode (RE) h) The 360º rotation cryogenic stage in the PFIB i) UHVCTS connected to the LEAP 6000 XR load lock j) APT sample puck loaded on to a pre-cooled piggyback puck.\u003c/p\u003e","description":"","filename":"Figure1.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5744208/v1/ca99285d69ae90739b79555c.jpg"},{"id":73236248,"identity":"2ebbff3b-f87d-4c0f-aa69-7a70c8da809e","added_by":"auto","created_at":"2025-01-08 05:02:45","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1088727,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Illustrative layout for workflow-1 (for quantifying H \u0026amp; O pickup during transfer process). Overlay of the mass-to-charge spectra peaks with peak indexing for (b) 0-80 Da, (c) 23-47 Da, and (d) 49-80 Da for the APT datasets collected using laser pulsing along with corresponding 1D composition profiles of (e) H and (f) O and (g) bulk H-concentration of the entire reconstruction for the baseline, buffer chamber (30 min), and glovebox (30 min) experimental conditions of workflow-1.\u003c/p\u003e","description":"","filename":"Figure2.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5744208/v1/8e1e25b335f805f75d0a9567.jpg"},{"id":73236249,"identity":"27548172-8887-4cda-bb80-02a91c65db03","added_by":"auto","created_at":"2025-01-08 05:02:45","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":769489,"visible":true,"origin":"","legend":"\u003cp\u003eThe mass-to-charge spectra for (a) 0-80 Da and (b) magnified view of 23-35 Da for the APT datasets collected using voltage pulsed mode analysis of the same needle sample and 1D composition profile showing the change in (c) H-concentration (d) O-concentration and (e) bulk H-concentration of the entire reconstructed dataset of baseline, buffer chamber (30 min), and glovebox (30 min) exposed conditions of workflow-1.\u003c/p\u003e","description":"","filename":"Figure3.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5744208/v1/c7f440e8dd0428d44ee87a8b.jpg"},{"id":73236250,"identity":"9652c66b-5b22-4c91-92ed-5fa3db13126c","added_by":"auto","created_at":"2025-01-08 05:02:45","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":974726,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Graphical representation of workflow-2 (Deuterium electrochemical charging experiment). The overlay of (b) mass-to-charge spectra, 1D concentration profiles of (c) hydrogen, (d)deuterium, and (e) oxygen, along with (f) comparison of the bulk concentration of H and D of and (g) ion maps of hydrogen and deuterium, for the APT experiments of baseline, D-charged, 30 min and 90 min warm up in buffer chamber conditions.\u003c/p\u003e","description":"","filename":"Figure4.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5744208/v1/a4bf3a02dc7f092cd40a2f02.jpg"},{"id":86699511,"identity":"ea6fe011-e817-4e9c-871d-62525d06c612","added_by":"auto","created_at":"2025-07-14 16:10:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5878781,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5744208/v1/012f519c-2e71-4279-8694-6f7d8f6be36d.pdf"},{"id":73236253,"identity":"636b42b7-9321-4689-8adf-7f1133aa1adc","added_by":"auto","created_at":"2025-01-08 05:02:45","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1011788,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-5744208/v1/42a40a55b722ed62294bbe24.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Insights from Quasi-in situ Cryogenic-Transfer Atom Probe Tomography for Analyzing Hydrogen Diffusion in Metallic Alloys","fulltext":[{"header":"Introduction","content":"\u003cp\u003eHydrogen is the lightest, smallest, and the most abundant element in nature. Hydrogen can diffuse into steel during manufacturing and service, leading to hydrogen embrittlement (HE)\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. This has significant implications for fields such as nuclear fission/fusion reactors, and for the development of future clean energy technologies, where hydrogen interaction with materials plays a critical role \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. The mechanistic interpretation of HE in iron alloys involves several theories, including hydrogen-enhanced decohesion (HEDE), hydrogen-enhanced local plasticity (HELP), adsorption-induced dislocation emission (AIDE), and hydrogen-enhanced strain-induced vacancies (HESIV)\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Experimental validation of these mechanisms requires spatially resolved mapping of hydrogen distribution in alloys at near-atomic resolution. Despite its importance, detecting and characterizing hydrogen at the nanoscale remains challenging\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTraditional methods, such as inert gas fusion (IGF)\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e, X-ray or neutron scatting or diffraction\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e and thermal desorption spectroscopy (TDS)\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e, have been widely used to quantify hydrogen content in various materials\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. However, these bulk analysis methods are unable to provide spatially resolved nanoscale distribution of hydrogen within a material\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Only a limited number of advanced analytical techniques can map hydrogen distribution in materials at a nanoscale spatial resolution, like Time-of-flight secondary ion mass spectrometry (ToF-SIMS)\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e, Scanning Kelvin Probe microscopy\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e, scanning tunneling microscope\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, and Atom probe tomography (APT)\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Among these methods, APT is the only technique that can provide three-dimensional compositional mapping of hydrogen distribution in materials at sub-nanometer scale spatial resolution\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. In recent years, an increasing number of studies have used APT to detect hydrogen\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e, deuterium\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e, and hydrides\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e in iron\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e, Al\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, Ti\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e and Zr\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e based alloys in which the hydrogen was introduced following direct ion implantation\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e, water corrosion\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e, gas charging\u003csup\u003e\u003cspan additionalcitationids=\"CR30\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e, electrochemical or cathodic charging\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. Despite the increasing usage of APT for hydrogen detection, the analysis is subject to extreme sensitivity to experimental details like residual hydrogen gas concentration in the analysis chamber, hydrogen isotope loading method, pre- and post-loading and handling of the APT sample, and parameters followed during acquisition, making quantitative analysis of hydrogen distribution still challenging\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSeveral researchers \u003csup\u003e\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e made significant progress toward analyzing hydrogen in materials using APT quantitatively or semi-quantitatively. Deuterium (\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003eH), an isotope of hydrogen with a larger atomic mass (2 Da) while exhibiting similar chemical reactivity, is often employed as a substitute for hydrogen in APT studies. This approach helps to mitigate the convolution between hydrogen that is intentionally charged into materials from the hydrogen already within the material and from the residual hydrogen signal from H in the APT analysis chamber\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Meier et al.\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e compared the voltage pulsed vs. pulsed UV laser APT in deuterium-charged and uncharged materials. While voltage-pulsing only yielded a clear \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003eH-peak (at 2 Da) for deuterium (denoted as D from here on) charged specimens, both D-charged and uncharged samples produced significant peaks at 2 Da in laser-pulsing APT, complicating peak assignment. Therefore, voltage-pulsing APT is often recommended for hydrogen analysis of conductive materials to achieve better analytical yields and improved quantification. Chen et al.\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e compared H/D electrochemical charging using electrolytes with different combinations of H\u003csub\u003e2\u003c/sub\u003eO, D\u003csub\u003e2\u003c/sub\u003eO, NaOH, and NaOD and demonstrated that D\u003csub\u003e2\u003c/sub\u003eO, combined with either NaOD or NaOH electrolytes, is equally effective in introducing deuterium into steel specimens, which can be followed by voltage-pulsing based APT analysis.\u003c/p\u003e \u003cp\u003eAtom probe tomography (APT) with cryogenic sample transfer capability is being increasingly used for quantitative analysis of hydrogen in metals as it can prevent the hydrogen out diffusion from metals with high H diffusivities\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan additionalcitationids=\"CR35 CR36\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e. This transfer capability employs an ultra-high vacuum cryogenic transfer shuttle (UHVCTS) suitcase that prevents the APT needle from exposure to the external environment and helps connect and transfer the APT needles between FIB, APT, and Glovebox. Researchers \u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan additionalcitationids=\"CR35 CR36\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e reported cryogenic sample transfer capability using UHVCTS as an effective method for studying materials that are sensitive to the environment, which includes magnesium \u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e,\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e, aluminum \u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e, and iron alloys \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. In addition, the use of cryogenic FIB milling and transfer has proven to be beneficial to minimize hydrogen uptake and hydride formation during sample preparation\u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. In steel, Chen et al.\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e employed cathodic or electrolytic charging followed by cryogenic transfer-APT to analyze hydrogen trapping in carbides, such as V-Mo-C and NbC, which revealed different H trapping mechanisms depending on carbide stoichiometry. In their follow-up study, Chen et al.\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e further identified that H trapping can occur both at interfaces and in carbon vacancies in the carbide bulk. Zhao et al.\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e used cryogenic transfer-APT to map H-trapping sites at grain boundaries and precipitates of aluminum alloys, contributing to a better understanding of hydrogen embrittlement in metals. More recently, Dallin et al.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e compared the deuterium pick up in pure iron (ferrite) and austenitic FeCrNi alloy after electrochemical charging followed by transfer to APT performed either at room temperature or after cryogenic-plunging prior to APT analysis, revealing that cryogenic plunge freezing and transfer prevented the deuterium out-diffusion from samples. These past studies underscored the critical role of ultra-high vacuum and cryogenic temperature handling in preventing hydrogen or deuterium loss during sample preparation and transfer to APT.\u003c/p\u003e \u003cp\u003eHowever, all the aforementioned literature discussion on the cryogenic sample transfer approach predominantly used the CAMEA LEAP 3000\u003csup\u003e2,20\u003c/sup\u003e, 4000\u003csup\u003e4,20,25,39,40\u003c/sup\u003e, and 5000\u003csup\u003e2,26,36,37\u003c/sup\u003e atom probe tomography systems. The LEAP 6000 XR is the latest generation of APT with deep UV laser (257.5 nm wavelength) and 52% detection efficiency (DE) compared to 3000 HR (green laser with 532 nm wavelength, 37% DE), 4000 XR (UV laser with 355 nm wavelength, 37% DE) and 5000 XR (UV laser with 355 nm wavelength, ~ 50% DE)\u003csup\u003e41\u003c/sup\u003e. Given that the LEAP 6000 XR is the latest APT model, very limited studies\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e,\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e have used LEAP 6000 XR APT for material characterization so far. Notably, no studies have been reported on hydrogen detection following cryogenic-transfer workflow into a LEAP 6000 XR so far. Therefore, we hereby focus on providing the first results from cryogenic-transfer APT utilizing a LEAP 6000 XR APT.\u003c/p\u003e \u003cp\u003eMoreover, studies to date, in analyzing hydrogen isotope diffusion within materials using cryogenic transfer-APT has predominantly focused on examining hydrogen-charged materials immediately after cryogenic transfer \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. Interestingly, to the best of our knowledge, no efforts have been made to investigate hydrogen out-diffusion from cryogenically transferred, hydrogen-charged samples as they are warmed up to different time periods. Given that APT analysis can be paused, allowing the sample to warm to room temperature within the APT buffer chamber vacuum before resuming analysis, this presents a quasi-in situ approach to study hydrogen out-diffusion from materials. Such an approach enables the analysis without significantly altering the surface of the APT needles. However, this method remains unexplored in the literature. In this work, we test the feasibility and address the challenges of analyzing hydrogen out-diffusion from materials using this quasi-in situ approach.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eCryogenic transfer procedure between PFIB, APT, and N\u003csub\u003e2\u003c/sub\u003e-Glovebox using UHVCTS\u003c/h2\u003e \u003cp\u003eThe experimental setup, including the plasma-focused ion beam (PFIB), APT, Ferrovac extension kit connected to an N₂-glovebox, and the UHVCTS used for shuttling Fe18Cr14Ni alloy needles between systems are given in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(a). The FeCrNi model alloy needle, with an apex diameter of 40\u0026ndash;100 nm, was prepared via electropolishing followed by annular milling in PFIB. The prepared needle can be seamlessly transferred between the APT, PFIB, and N\u003csub\u003e2\u003c/sub\u003e-glovebox using the UHVCTS, with each system equipped with dedicated docking stations for the UHVCTS suitcase, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea. The electrochemical deuterium charging experiment is conducted inside the N\u003csub\u003e2\u003c/sub\u003e-glovebox.\u003c/p\u003e \u003cp\u003eDetailed photographs of individual instrumentation and parts of the cryogenic transfer-APT workflow are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(b-j). The Ferrovac extension kit allows seamless integration between the UHVCTS and the N\u003csub\u003e2\u003c/sub\u003e glovebox (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). A cryogenic load lock with a vertical receptacle elevator allows the transfer of an APT sample puck into and out of the LN\u003csub\u003e2\u003c/sub\u003e basin situated within the N2 glove box (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec-d). The supporting tool and guide rail within the LN\u003csub\u003e2\u003c/sub\u003e basin facilitate the manual removal of the APT puck with the pre-loaded needle sample and load it to the receptacle base (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(d-f)). For electrochemical charging, the APT needle sample pre-loaded in the APT puck is oriented upside down using a puck manipulator located inside the glove box, allowing only the apex of the sample to be immersed in a 0.1 M NaOD electrolyte with 8 g/L thiourea for deuterium electrochemical charging at -2.2 V (vs. Ag/AgCl) for 300 seconds, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg. During D-charging, the LN\u003csub\u003e2\u003c/sub\u003e basin was filled with liquid nitrogen (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb), for cooling the receptacle base and supporting tool. Following D-charging, the APT puck with the needle sample was placed onto the LN\u003csub\u003e2\u003c/sub\u003e-cooled receptacle base within 30 seconds of stopping the power supply, transferred back to the cryogenic load lock, and moved to the UHVCTS. It was subsequently transferred to the 360 \u003csup\u003eo\u003c/sup\u003e rotation cryogenic stage installed within the PFIB for annular milling (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eh). The final needle sample was then transferred from PFIB to APT using UHVCTS. The LN\u003csub\u003e2\u003c/sub\u003e dewar attached to the UHVCTS maintained the needle at cryogenic temperatures during the transfer, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ei. The piggyback puck, pre-cooled in the analysis chamber (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ej), ensures the needle remains at cryogenic temperatures while being transported from the APT load lock to the analysis chamber for the APT analysis conducted in voltage or laser pulsing modes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eQuantifying the hydrogen and oxygen pickup in FeCrNi alloys during the cryogenic transfer process\u003c/h3\u003e\n\u003cp\u003eFirst, we aimed to quantify the hydrogen (H) and oxygen (O) pickup on FeCrNi needle samples during the transfer process between the APT buffer chamber and N\u003csub\u003e2\u003c/sub\u003e-glovebox under laser and voltage pulsing modes, as presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea. The FeCrNi needle was prepared via electropolishing, followed by annular milling in PFIB. The prepared needle was first transferred to the APT using the UHVCTS for collecting a baseline data, first in voltage and then in laser pulsing modes, collecting 1\u0026nbsp;million ions in each analysis. Subsequently, the APT analysis was interrupted, and the needle sample was taken out of the analysis chamber and was transferred to the N\u003csub\u003e2\u003c/sub\u003e-glovebox using the UHVCTS and held in the glove box for 30 minutes before transferring it back into the APT analysis chamber and conducting laser and then voltage pulsing mode APT analysis. An additional dataset of 0.5\u0026nbsp;million ions was acquired for each APT analysis to quantify the O and H pickup that occurred cumulatively due to the 30-minute glove box exposure and the transfer process to and from the glove box. After that, the APT analysis was again interrupted, and the same needle sample was allowed to warm up to room temperature in the APT buffer chamber (maintained between 1.6E-8 to 1.2E-8 torr) for 30 minutes, followed by transferring the sample back into the APT analysis chamber. The buffer chamber vacuum recorded during the 30 minutes hold in buffer chamber is presented in Supplementary Fig.\u0026nbsp;1. The sample was re-analyzed first in laser pulsing mode and then in voltage pulsing mode immediately after, and an additional dataset of 0.7\u0026nbsp;million ions each was collected to assess how much O and H pickup occurred in the sample during the 30-minute exposure to the buffer chamber vacuum and how the laser vs voltage mode influences the compositional quantification of H and O under the same conditions.\u003c/p\u003e \u003cp\u003eThe mass-to-charge spectra from the APT dataset collected in laser pulsing mode for baseline, buffer chamber (30 min), and glovebox (30 min) conditions are shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(b-d). The Laser pulsed mode mass-to-charge spectra for all conditions exhibited similar peaks for H, H\u003csub\u003e2\u003c/sub\u003e, C, and O in the +\u0026thinsp;1 charge state and C, Fe, Cr, and Ni in the +\u0026thinsp;2 charge state, and Fe, Cr, and Ni peaks in the +\u0026thinsp;1 charge state for all conditions, as indexed in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(b-d). Moreover, oxide molecular peaks of Fe, Cr, and Ni in both +\u0026thinsp;1 and +\u0026thinsp;2 charge states were observed across all conditions in laser pulsing mode (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). For all compositional analysis, overlapping peaks for Cr\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e/Fe\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e (at 27 Da), Fe\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e/Ni\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e (at 29 Da), Ni\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e/O\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e (at 32 Da), Fe\u003csup\u003e+\u0026thinsp;1\u003c/sup\u003e/Cr\u003csup\u003e+\u0026thinsp;1\u003c/sup\u003e (at 54 Da), and Fe\u003csup\u003e+\u0026thinsp;1\u003c/sup\u003e/Ni\u003csup\u003e+\u0026thinsp;1\u003c/sup\u003e (at 58 Da) was deconvoluted using non-overlapping isotopic peaks.\u003c/p\u003e \u003cp\u003eA 10 nm diameter cylinder was used to quantify the 1D composition profile of the baseline APT data reconstruction where the cylinder region of interest was specifically placed well below the top surface of the reconstruction to avoid the PFIB damage layer. This allowed us to quantify the composition of the needle surface at the end of the baseline clean up APT analysis before it was exposed to buffer chamber or glove box environments. In the case of the APT reconstructions after 30 min exposure in buffer and glove box, the 10nm cylinder ROI was placed to quantify the composition change right from the top surface of those reconstructions. The 1D concentration profiles of Fe, Cr, Ni, O, H, C, and N for laser pulsing mode datasets are provided in Supplementary Fig.\u0026nbsp;2. The hydrogen composition profiles of baseline, 30-minute buffer chamber, and 30-minute glovebox conditions in laser pulsed mode are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee. The hydrogen detected in the baseline clean-up APT analysis condition may result from the hydrogen introduced to the sample during the electropolishing and PFIB annular milling or from the desorption of absorbed hydrogen from the APT analysis chamber. After 30 min exposure of the same sample to the buffer chamber or glove box environment, the hydrogen concentrations within the top 0.6 nm near the top surface of the reconstructions increased considerably compared to the end of baseline APT analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee). Additionally, from the oxygen 1D composition profiles in each of those conditions from the laser-pulsed mode datasets (given in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef) it is clear that oxygen concentrations within the top 0.7 nm near the surface of the reconstructions increased compared to the baseline after 30 min exposure in the buffer chamber and glove box, suggesting near-surface oxidation of the needle samples even during the exposure to the buffer chamber vacuum and glove box environment and during the UHVCTS transfer. The bulk hydrogen concentration quantified from the entire reconstructions after 30 min exposure in the buffer chamber and glove box clearly showed an increase when compared with the H-concentration in the baseline APT data (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eg).\u003c/p\u003e \u003cp\u003eAs described above, after 30 min exposure to the buffer chamber and to glove box environments, first, a laser pulsed mode APT analysis was conducted. Each of those laser-pulsed APT analyses was interrupted after collecting at least 0.5\u0026nbsp;million ions, and a voltage-pulsed APT analysis was conducted immediately after to quantify the change between laser and voltage modes of analysis. The mass-to-charge spectra from the APT dataset collected in back-to-back voltage pulsing modes for baseline, buffer chamber (30 min), and glovebox (30 min) conditions are shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a-b). The voltage-pulsed mode mass-to-charge spectra for all conditions exhibited similar peaks for H, C, and O in the +\u0026thinsp;1 charge state and C, Fe, Cr, and Ni in the +\u0026thinsp;2 charge state, as indexed in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb. Only for the APT reconstruction of the baseline cleanup step, xenon (Xe) peaks were observed at 64\u0026ndash;68 Da, resulting from Xe beam damage during PFIB sample preparation (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea).\u003c/p\u003e \u003cp\u003eThe 1D concentration profiles of Fe, Cr, Ni, O, H, C, and N for the voltage pulsing mode datasets are provided in Supplementary Fig.\u0026nbsp;3. The 1D composition profile of H in the three back-to-back voltage analyses given in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec still showed an increased H concentration within the top 0.3 nm of the reconstructions after exposure to the buffer chamber and glove box. Essentially, the H concentration measured at the end of the laser pulsed analysis and the back-to-back voltage analysis for each of these conditions appeared to differ. The oxygen 1D concentration profiles from the back-to-back voltage analysis show no apparent surface oxidation, which can be expected since the top oxidized surface of needle samples were already analyzed in the laser mode before (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). Moreover, like the observations in the laser mode datasets, in the back-to-back voltage mode datasets also there was clear evidence for increased bulk H concentration in the samples after exposure to the glove box and buffer chamber vacuum for 30 mins (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee). However, the quantified amount of hydrogen was substantially lower in the case of voltage mode datasets versus laser mode dataset for the same needle sample for the baseline and 30 min exposed conditions. Meir et. al and other authors showed the pulsed laser mode led to the H\u003csub\u003e2\u003c/sub\u003e peak at 2Da in the case of UV laser\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. This observation appears to remain consistent in the case of the deep UV laser used in the LEAP 6000 XR, and therefore possibly directly contributing to an over-estimation of the hydrogen concentration when analyzed in pulsed laser mode. Also given the peak at 2Da will overlap with the deuterium peak, for the electrochemical deuterium charging experiments in workflow 2, we only used voltage mode of analysis.\u003c/p\u003e \u003cp\u003eThis detailed understanding of the changes to the near-surface H and O concentration of APT needle samples during the transfer process to APT buffer chamber and glove box allows us to better understand the changes in the composition of deuterium-charged samples measured before and after cryogenic transfer APT, which is described next.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eQuantification of deuterium pickup and desorption kinetics from the electrochemical deuterium charged FeCrNi model alloy\u003c/h3\u003e\n\u003cp\u003eThe quantification of deuterium pickup after electrochemical deuterium charging in the N\u003csub\u003e2\u003c/sub\u003e-glovebox and deuterium desorption kinetics after sequential warm-up inside the APT buffer chamber is investigated in the second workflow, as presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea. Initially, a second needle of FeCrNi alloy is prepared via electropolishing, followed by PFIB annual milling. The PFIB-prepared FeCrNi needle was initially transferred to the APT via the UHVCTS for baseline measurements in voltage pulsing mode (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). After collecting the baseline APT data, the needle was transferred to the glovebox via the UHVCTS, facilitated by the Ferrovac extension kit for the D-charging experiment (at -2.2 V (vs. Ag/AgCl) for 300 seconds in 0.1 M NaOD electrolyte with 8 g/L thiourea as a recombination poison). Post-charging, the needle was immediately plunged in LN\u003csub\u003e2\u003c/sub\u003e, frozen, and transferred to PFIB for annular milling and then to APT using the Ferrovac extension kit and UHVCTS and analyzed in voltage-pulsed mode to quantify the deuterium pickup. After collecting at least 1\u0026nbsp;million ions, the APT experiment was interrupted and the needle sample was taken out of the APT analysis chamber and then placed in the APT buffer chamber carousel at room temperature and held for 30 minutes, followed by voltage pulsing APT analysis. The APT analysis was again interrupted after collecting 1\u0026nbsp;million ions and then transferred back to the buffer chamber and held for an additional 90 minutes at room temperature and transferred back into the analysis chamber and analyzed again in voltage pulsed mode. During the warm-up, the buffer chamber vacuum fluctuations were recorded and presented in Supplementary Fig.\u0026nbsp;4. The buffer chamber vacuum fluctuated between 4E-8 and 1E-7 Torr during the 30-minute hold and between 3.5E-8 and 4.5E-7 Torr during the 90-minute hold. This 30-minute and 90-minute warm-up of the deuterium-charged sample in the buffer chamber, followed by APT analysis, was conducted to analyze the deuterium out-diffusion from the sample at room temperature.\u003c/p\u003e \u003cp\u003eThe APT mass-to-charge spectra of baseline, deuterium charged, and after 30 min and 90 min warm up in buffer chamber exhibited similar peaks for H, O, N, Fe, Ni in +\u0026thinsp;1 charge state and C, Fe, Cr, and Ni in +\u0026thinsp;2 charge state (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb). Additionally, the oxide molecular peaks of Fe, Cr, and Ni in +\u0026thinsp;1 and +\u0026thinsp;2 charge states are observed in all four conditions. The oxide molecular peaks were most predominant in D-charged conditions. The carbon peaks at 6 and 12 Da were observed only initially in the baseline cleanup APT reconstruction, which could be minor surface contamination. The deuterium peak at 2 Da was observed in D-charged, buffer chamber 30 min and 90 min conditions.\u003c/p\u003e \u003cp\u003eLike the data analysis for workflow 1, a 10 nm diameter cylinder was used to quantify the 1D composition profile of the baseline clean-up APT reconstruction where the cylinder region of interest was specifically placed well below the top surface of the reconstruction to avoid the PFIB damage layer. This allowed us to quantify the composition of the needle surface at the end of the baseline clean-up APT analysis before it was electrochemically charged with deuterium. In the case of the APT reconstructions, after deuterium charging and warm-up for 30 min and 90 min in the buffer chamber, the 10nm cylinder ROI was placed to facilitate the quantification of the composition change right from the top surface of those reconstructions. The 1D concentration profiles of Fe, Cr, Ni, O, H, C, and N for the baseline, D-charged, 30-minute, and 90-minute warmed samples in the buffer chamber are provided in Supplementary Fig.\u0026nbsp;5. The overlay of 1D composition profiles of H, D, and O in the baseline, D-charged, 30-min, and 90-min warmed samples in the buffer chamber are given in Figs.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec, d, and e, respectively. At the end of the baseline condition, the H, D, and O concentrations were notably low. However, after the electrochemical deuterium charging and cryogenic transfer of FeCrNi samples from the N2-glove box to PFIB and then to LEAP 6000XR using UHVCTS resulted in a significant increase in the near-surface concentrations of H and O, which interestingly coincided with a near-surface depletion of D. But the D concentration deeper in the needle was highest after the electrochemical charging and cryogenic transfer. The bulk D concentration is quantified and plotted in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ef, along with corresponding ion maps in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eg. From Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ef, it is evident that the overall bulk concentration of Deuterium quantified in the reconstruction of the D-charged sample reduced in subsequent reconstructions after warm-up for 30 min and 90 min in the buffer chamber vacuum. Following D-charging, the bulk D concentration peaked at ~\u0026thinsp;1.4 at. % and gradually declined to ~\u0026thinsp;1.1 at. % after 30 minutes and ~\u0026thinsp;0.7 at. % after 90 minutes of warming at room temperature in the buffer chamber vacuum, signifying the D out-diffusion from the sample.\u003c/p\u003e \u003cp\u003eInterestingly, following the 90-minute warmup in buffer chamber, although the bulk deuterium concentration decreased, the local deuterium concentration near to top surface of reconstruction within ~\u0026thinsp;1 nm depth increased to ~\u0026thinsp;7 at. %. It is plausible that during the 90-minute warmup in the buffer chamber, a continuous thin surface oxide layer formed on the needle surface, which likely acted as a diffusion barrier leading to a near-surface accumulation of deuterium. These findings underscore the dynamic desorption behavior of deuterium and the interactions between hydrogen, oxygen, and the FeCrNi needle sample after deuterium charging and during warm-up to room temperature in the buffer chamber environment.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, we first analyzed the nanoscale compositional changes near the top surface of an austenitic Fe18Cr14Ni alloy needle sample during the cryogenic transfer process and on prolonged exposure to the buffer chamber vacuum at room temperature. To achieve this, we did a series of experiments using laser and voltage modes on the same FeCrNi alloy needle sample. This allowed us to make quantitative comparisons of hydrogen and oxygen compositions across different exposure conditions of the sample. The needle sample was first analyzed in voltage and laser mode to obtain a quantitative analysis of H and O within the sample initially. Subsequent exposure of the same needle sample in the buffer chamber vacuum for 30 min revealed surface oxidation and hydrogen absorption. The same sample was also transferred to the glove box using UHVCTS, then held in the glovebox for 30 minutes and transferred back into APT, which led to a higher extent of oxidation and H-ingress. The comparison of back-to-back laser pulsed and voltage pulsed analysis revealed that laser-pulsing tends to overestimate the Hydrogen concentration in the samples, and the H\u003csub\u003e2\u003c/sub\u003e peak appeared at 2Da even with the deep UV laser used in LEAP 6000 XR. This understanding of the influence of sample exposure during the transfer process was then used to better interpret the results of a second needle sample that was deuterium-charged electrochemically and cryogenically transferred to PFIB and then to APT using UHVCTS. In addition, subsequent measurement of changes in Deuterium, Hydrogen, and oxygen concentrations in the same needle due to 30 min and 90 min warm up to room temperature within the buffer chamber aided in analyzing the deuterium-desorption kinetics from the deuterium-charged FeCrNi alloy sample. The deuterium concentration in the sample progressively reduced during the warmup time in the buffer chamber, which points to the possibility of using such a quasi-in situ approach to analyze hydrogen isotope desorption from a wide class of materials. Presumably maintaining the buffer chamber vacuum to levels below the 5E-8 torr could further reduce surface oxidation during the controlled warm up of samples and that could improve the quantification of deuterium out-diffusion by avoiding the formation of a surface oxide layer altogether. The findings from this work provide a precise measure of the factors to be considered during the cryogenic transfer APT experiments and its potential to achieve a nanoscale understanding of hydrogen diffusion kinetics within metal alloys, which could be applied to a broad class of metal alloys. We anticipate this approach to be particularly suitable for analyzing the influence of specific defects and alloy chemistry changes for modifying the hydrogen diffusion kinetics in materials, which could be invaluable both for better understanding hydrogen embrittlement mechanisms and for hydrogen storage material development efforts.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cp\u003eFe18Cr14Ni alloy was fabricated by induction melting high-purity elements, followed by casting and homogenizing through five remelting cycles. These alloys were subsequently cold rolled to reduce their area by 50% and recrystallized into 3 mm thick sheets by annealing at 900 ℃ for 4 hours. Using electric discharge machining, bars with a 1 mm\u0026sup2; cross-section were cut from the fabricated Fe18Cr14Ni alloy. These bars were ground and polished on all sides, progressively using finer grits to a 1 mm diamond suspension. The prepared 1 mm\u0026sup2; bars were sharpened into needles using a two-step polishing procedure. Initially, coarse polishing was performed with a 25% perchloric acid solution in glacial acetic acid. This was followed by fine polishing using a 2% perchloric acid solution in 2-butoxyethanol.\u003c/p\u003e \u003cp\u003eThermo Fisher Helios Hydra plasma-focused ion beam (FIB) with Xe plasma was used to final polish the needles to 40\u0026ndash;80 nm apex diameter following the annular milling process. The ion milling process was carried out at a voltage of 30 kV, gradually decreasing the current, with the final milling step performed at 2 kV and 10 pA. Atom probe tomography (APT) was conducted using a CAMECA local electrode atom probe (LEAP) 6000 XR, operating in voltage pulsing mode with a 20% pulse fraction and laser mode with 25pJ laser pulse energy while maintaining 200KHz pulse frequency and 0.5% Detection rate. The sample temperature was maintained at 50K for all APT data collection in workflow 1. The collected APT data was reconstructed and analyzed using Interactive Visualization and Analysis Software (IVAS). The ultra-high vacuum cryo transfer shuttle (UHVCTS) suitcase was used to transfer samples between plasma-focused ion beam (PFIB), APT, and N\u003csub\u003e2\u003c/sub\u003e-glovebox. In workflow 2, the deuterium desorption experiments were conducted by warming the samples within the buffer chamber for 30 and 90 minutes and followed by APT data collection in voltage pulsing mode. For the APT experiments of Deuterium charged samples, the sample temperature was maintained at 70K. During the warm-up, the buffer chamber vacuum fluctuated between 5E-8 Torr and 4E-7 Torr.\u003c/p\u003e \u003cp\u003eElectrochemical experiments were carried out using an Ossila potentiostat with a FIB-prepared FeCrNi needle acting as the working electrode (WE), Ag/AgCl (0.1 M KCl) as the reference electrode (RE), and Pt wire as the counter electrode (CE). The FIB-prepared FeCrNi needles were subjected to -2.2 V\u003csub\u003eAg/AgCl\u003c/sub\u003e constant voltage for 300 seconds in 0.1 M NaOD with 8g/L Thiourea electrolytes for deuterium electrochemical charging. Prior to the electrochemical experiments, the open circuit potentials were recorded while the specimen was stabilized in the test electrolyte for 100 seconds. All the electrochemical experiments were conducted inside the N\u003csub\u003e2\u003c/sub\u003e glovebox while maintaining\u0026thinsp;\u0026lt;\u0026thinsp;1 ppm oxygen and \u0026lt;\u0026thinsp;10 ppm moisture.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompeting Interest\u003c/h2\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eV.B.V. performed the experiments, including electropolishing, FIB, APT, electrochemical charging, and APT data analysis. Z.L. contributed to FIB and APT experiments. V.S. and V.B.V. led the installation of the glovebox and Ferrovac extension kit. A.D. procured the funding and conceptualized the project and guided the APT data analysis and supervised the entire project. The original manuscript was drafted by V.B.V. and reviewed and revised by all authors.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis research was supported by the Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences, and Engineering Division as a part of the Early Career Research Program FWP 76052. V.B. acknowledges Jack Grimm for the discussions related to APT and support in APT data reconstruction. V.B. acknowledges Mengkong (Andrew) Tong for the electrochemical charging assembly fixture development.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data can be made available upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eChen, Y.-S.\u003cem\u003e et al.\u003c/em\u003e Atom Probe Tomography for the Observation of Hydrogen in Materials: A Review. \u003cem\u003eMicroscopy and Microanalysis\u003c/em\u003e \u003cstrong\u003e29\u003c/strong\u003e, 1-15 (2023). https://doi.org/10.1093/micmic/ozac005\u003c/li\u003e\n\u003cli\u003eBreen, A. 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Comparison of Hydrogen Resilience of Three Different Corrosion-Resistant Martensitic Steels. https://doi.org/10.2139/ssrn.5028452\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"npj-materials-degradation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjmatdeg","sideBox":"Learn more about [npj Materials Degradation](http://www.nature.com/npjmatdeg/)","snPcode":"41529","submissionUrl":"https://submission.springernature.com/new-submission/41529/3","title":"npj Materials Degradation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-5744208/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5744208/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCryogenic-transfer atom probe tomography (APT) has emerged as a powerful technique for nanoscale compositional analysis of hydrogen segregation in materials, offering critical insights into hydrogen embrittlement mechanisms. However, accurate quantification of hydrogen concentration in materials requires careful handling of sample exposure during the cryogenic transfer-APT process. Therefore, we describe the quantitative changes in the surface composition of hydrogen and oxygen in an austenitic FeCrNi model alloy during the ultrahigh vacuum transfer using the state-of-the-art LEAP 6000 XR APT, employing both deep UV laser-assisted and voltage pulsed modes of analysis. These insights were applied to interpret deuterium desorption from the FeCrNi alloy at room temperature after electrochemical deuterium-charging. The findings underscore the importance of managing sample exposure throughout the cryogenic-transfer APT process and introduce a novel quasi-in situ approach to analyzing hydrogen out-diffusion kinetics, which could be extended to a broader range of metallic alloys.\u003c/p\u003e","manuscriptTitle":"Insights from Quasi-in situ Cryogenic-Transfer Atom Probe Tomography for Analyzing Hydrogen Diffusion in Metallic Alloys","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-08 05:02:40","doi":"10.21203/rs.3.rs-5744208/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-01-27T22:54:22+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-27T07:56:00+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-27T02:29:09+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-22T01:38:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"323725189777794212968497235912504072863","date":"2025-01-14T01:03:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"174610934854642977010573693157364518349","date":"2025-01-08T20:43:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"136248440816454638150902014600682741077","date":"2025-01-07T13:22:25+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-01-06T22:46:57+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-06T22:44:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-06T12:13:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"npj Materials Degradation","date":"2025-01-01T02:20:18+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"npj-materials-degradation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjmatdeg","sideBox":"Learn more about [npj Materials Degradation](http://www.nature.com/npjmatdeg/)","snPcode":"41529","submissionUrl":"https://submission.springernature.com/new-submission/41529/3","title":"npj Materials Degradation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a6f47b1a-adc9-458d-99a5-72ebc579b1b1","owner":[],"postedDate":"January 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":42500447,"name":"Physical sciences/Materials science/Structural materials/Metals and alloys"},{"id":42500448,"name":"Physical sciences/Materials science/Materials for energy and catalysis"},{"id":42500449,"name":"Physical sciences/Materials science/Techniques and instrumentation"}],"tags":[],"updatedAt":"2025-07-14T16:06:48+00:00","versionOfRecord":{"articleIdentity":"rs-5744208","link":"https://doi.org/10.1038/s41529-025-00626-2","journal":{"identity":"npj-materials-degradation","isVorOnly":false,"title":"npj Materials Degradation"},"publishedOn":"2025-07-09 15:57:44","publishedOnDateReadable":"July 9th, 2025"},"versionCreatedAt":"2025-01-08 05:02:40","video":"","vorDoi":"10.1038/s41529-025-00626-2","vorDoiUrl":"https://doi.org/10.1038/s41529-025-00626-2","workflowStages":[]},"version":"v1","identity":"rs-5744208","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5744208","identity":"rs-5744208","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}