Breaking the wear resistance dilemma of nanograined metals with dispersive internal gradient heterostructure

Breaking the wear resistance dilemma of nanograined metals with dispersive internal gradient heterostructure | 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 Breaking the wear resistance dilemma of nanograined metals with dispersive internal gradient heterostructure Xiang Chen, Zhaoshuo Chen, Xianzhi Bian, Yan Lin, Fei Liang, Yuntian Zhu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9233027/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Friction and wear impose fundamental constraints on the reliability and lifetime of structural materials. Although nanograined (NG) metals with grain sizes below ~ 100 nm exhibit exceptional strength and hardness, their wear resistance is intrinsically constrained by strain localization at ambient temperatures and pronounced grain coarsening at elevated temperatures. Here, we address this long-standing problem by introducing dispersive gradient nanograined domains into an ultrafine-grained pure nickel via micro-scale titanium incorporation. This internal gradient architecture reduces wear rates by an order of magnitude across a broad temperature range (25–800°C) compared with homogeneous NG metals. The exceptional wear resistance arises from the combined thermal and mechanical stability of the ultrafine-grained matrix and the mitigation of strain localization at gradient interfaces. Compatible with scalable electrodeposition, this strategy establishes a broadly applicable materials design paradigm for achieving durable metallic surfaces under harsh tribological conditions. Physical sciences/Materials science/Structural materials/Mechanical properties Physical sciences/Materials science/Structural materials/Metals and alloys Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Friction and wear are pervasive sources of energy dissipation and material degradation at contacting interfaces 1 – 6 , critically limiting the efficiency and service life of engineering systems from heavy-load gears to mining and rolling machinery. Minimizing friction and wear is therefore essential for both energy efficiency and operational reliability 7 – 14 . Conventional strategies to improve tribological performance primarily involve interfacial lubrication 15 and surface hardening 16 , 17 . However, lubrication often fails under harsh environments, particularly at elevated temperatures 18 , 19 . Surface hardening through second-phase particle reinforcement 20 or nanoscale grain refinement 21 – 25 , faces significant challenges in achieving long-term stability. In particle-reinforced materials, excessive mechanical incompatibility at matrix/particle interfaces can trigger interfacial cracking, leading to severe delamination during sliding 26 . These limitations underscore the urgent need for innovative microstructural design strategies that combine high strength with sustained wear resistance under extreme conditions. While nanograined (NG) metals are celebrated for their remarkable strength and hardness, their tribological performance remains a major issue in harsh environments. At ambient temperatures, NG metals exhibit high friction coefficients (0.6–0.8) and elevated wear rates (~ 10 − 4 mm 3 /(N·m)) under high-load sliding, primarily due to strain localization at grain boundaries 27 – 29 . This results in brittleness and surface delamination, which represents an intrinsic “Achilles’ heel” of NG metals 30 , 31 . At elevated temperatures, the hurdle is exacerbated by grain coarsening 32 – 34 , which compromises their structural integrity and further diminishes wear resistance (Fig. 1 a). Together, strain localization and structural instability constitute a long-standing wear-resistance dilemma for NG metals. Gradient nanograined (GNG) surface layers with submillimeter thickness have emerged as a promising strategy to mitigate strain localization by introducing spatial variations in grain size and strength 35 – 38 . By matching local yield stresses to the applied tribological stresses, such surface gradients can reduce friction and wear at room temperature 39 . However, maintaining low friction and wear under repeated sliding—particularly at elevated temperatures—remains a formidable challenge. Progressive removal of topmost nanograined layer, coupled with grain coarsening and renewed strain localization at nanograin interfaces, often leads to a rapid transition from low to high friction (~ 0.3→0.8) and accelerated material loss to ~ 10 − 4 mm 3 /(N·m)) 40 . Critically, sustained low friction and wear across a broad temperature range has yet to be demonstrated. To address these limitations, we engineered dispersive, internally distributed gradient nanograined domains within an ultrafine-grained (UFG) pure Ni matrix by incorporating micro-scale Ti particles. Owing to the limited miscibility of the Ni-Ti binary system, the Ti particles effectively stabilize the Ni microstructure and create pronounced grain size gradients embedded throughout the bulk, extending over micrometer length scales. Unlike surface-confined gradient layers, which fail as the topmost nanograins are progressively removed during sliding, dispersive internal gradients remain active throughout the contacting volume, suppressing grain coarsening and mitigating strain localization at gradient interfaces under tribological loading (Fig. 1 b). This heterostructure reduces wear rates by an order of magnitude from 25 to 800°C compared with homogeneous NG metals. Importantly, this gradient heterostructure concept is also demonstrated in Ni–Ta and Ni–Nb alloys, establishing a scalable, electrodeposition-compatible design paradigm for durable, high-performance metallic materials under harsh tribological environments. Results Using direct-current electrodeposition, we fabricated three representative architectures: homogeneous NG Ni, NG Ni-Ti, and gradient UFG (G-UFG) Ni-Ti. The NG Ni deposit exhibits uniform nanograined structure with an average grain size of ~ 53 nm (Fig. 2 a). Incorporation of micro-scale Ti particles serve as heterogeneous nucleation sites, refining the surrounding Ni matrix and producing smaller grains near the particles. In NG Ni-Ti, a high density of Ti particles generates uniform nanograins between adjacent particles, with an average grain size of 24 nm (Fig. 2 b). In contrast, G-UFG Ni-Ti displays pronounced internal gradient nanograined structure surrounding the Ti particles, as revealed by transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD) taken from the same region (Fig. 2 c,d), with grain sizes increasing from nanocrystalline near Ti particles to ultrafine grains with distance. Quantitative analysis (Fig. 2 e) reveals that the Ni grain size between neighboring Ti particles spans ~ 23–244 nm. This gradient is confined to a localized region spanning ~ 2–3 µm while the matrix retains a predominantly UFG structure (Supplementary Fig. 1). Reciprocating sliding tests across 25–800°C reveal the superiority of the G-UFG architecture. For NG Ni, the coefficient of friction (COF) rises sharply from ~ 0.29 at 25 ℃ to ~ 0.55 at 600 ℃ and subsequently decreases to ~ 0.46 at 800 ℃. For NG Ni-Ti, the COF basically fluctuates between 0.36 and 0.38, while G-UFG Ni-Ti increases gradually from 0.31 to 0.41 (Fig. 2 f). At both 25°C and 800°C, wear scars are narrow and shallow in G-UFG Ni-Ti, contrasting with deep scars in NG Ni and NG Ni-Ti (Fig. 2 g). Correspondingly, wear rates of NG Ni increases by two orders of magnitude, from ~ 2.14⋅10 − 6 mm 3 /(N·m) at 25 ℃ to ~ 3.29⋅10 − 4 mm 3 /(N·m) at 800 ℃. NG Ni-Ti increases moderately from ~ 9.95⋅10 − 6 mm 3 /(N·m) at 25 ℃ to ~ 4.55⋅10 − 5 mm 3 /(N·m) at 800 ℃. In contrast, G-UFG Ni-Ti maintains the lowest wear rates across the entire temperature range, from 1.74⋅10 − 7 mm 3 /(N·m) to 2.12⋅10 − 5 mm 3 /(N·m) (Fig. 2 h). Compared with NG metals exhibiting widely scatted wear rates spanning from 10 − 6 to 10 − 3 mm 3 /(N·m) 41–48 , the G-UFG structure achieves both a low COF (~ 0.3) and a substantially reduced wear rate (~ 1.7⋅10 − 7 mm 3 /(N·m)) at room temperature (Fig. 2 i). Across 25–800°C, the G-UFG structure consistently outperforms NG Ni 49 and Ni-based alloys 50 – 53 , reducing wear rates by approximately an order of magnitude (Fig. 2 j). To elucidate the microstructural origins of the superior wear resistance of the G-UFG architecture, we examined subsurface regions of NG Ni, NG Ni-Ti and G-UFG Ni-Ti after sliding at 25 ℃ and 800 ℃. After 25 ℃ sliding, NG Ni develops a two-layer subsurface structure (Fig. 3 a): a thick tribolayer (~ 2 µm) of NiO nanograins with an average grain size of ~ 12 nm (Supplementary Fig. 2), and an adjacent dynamic recrystallization (DRX) layer with coarsened grains (~ 250–300 nm). Massive cracks are identified within the brittle tribolayer and along the tribolayer/DRX interface. NG Ni-Ti exhibits a similar layered configuration (Fig. 3 b), consisting of a topmost NG tribolayer containing NiO and TiO 2 atop a DRX layer (Supplementary Fig. 2). Multiple microcracks nucleate and propagate within the tribolayer. In contrast, G-UFG Ni-Ti displays a tribolayer, a DRX layer and an undeformed matrix (Fig. 3 c). Notably, the original Ti particles severely deform and transform from irregular blocks to thin lamellae, with minimum thicknesses of ~ 23 nm and lengths exceeding 5 µm, as confirmed by EDS mapping in Supplementary Fig. 3. Even after sliding at 800 ℃, the G-UFG architecture maintains exceptional structural intergrity. NG Ni develops a tribolayer (~ 6 µm thick) composed of equiaxed NiO nanograins, within which microcracks are prevalent (Fig. 3 d and Supplementary Fig. 4). Similarly, pronounced microcracks persist in the nanostructured tribolayer containing NiO and TiO 2 in NG Ni-Ti (Fig. 3 e and Supplementary Fig. 4). In contrast, G-UFG Ni-Ti retains a stable three-layer subsurface architecture comprising a thin, crack-free tribolayer, an underlying DRX layer and an undeformed matrix (Fig. 3 f). We quantified microstructural stability by analyzing grain growth in the DRX layer using the ratio \(\:\text{d}/{\text{d}}_{\text{0}}\) , where d and d 0 denote the DRX and original grain sizes, respectively. At 25 ℃, the \(\:\text{d}/{\text{d}}_{\text{0}}\) value for G-UFG Ni-Ti is only ~ 1.46 (Fig. 3 g), compared with 4.96 of NG Ni and 2.23 of NG Ni-Ti. At 800 ℃, the \(\:\text{d}/{\text{d}}_{\text{0}}\) value in the DRX layer for G-UFG Ni-Ti is only ~ 2.99, far lower than that of NG Ni (16.5) and NG Ni-Ti (36.45), as shown in Fig. 3 h. Beyond ~ 6 µm depth, the undeformed matrix retains its original grain size, demonstrating exceptional microstructural stability. Correspondingly, the worn surfaces of NG Ni and NG Ni-Ti exhibit severe peeling and delamination, whereas G-UFG Ni-Ti maintains smooth, intact wear scars at both 25°C and 800°C (Supplementary Fig. 5). Micro-pillar compression and annealing experiments further confirm the superior stability of the dispersive internal gradient architecture (Fig. 4 ). Under uniaxial compression, NG Ni and G-UFG Ni-Ti both exhibit homogeneous deformation without local shear failure. In contrast, NG Ni-Ti develops a pronounced shear band along the Ni/Ti interface with several microcracks, indicating severe strain localization (see Fig. 4 a-c). Subsurface microstructures (~ 3 µm from pillar tops) reveal different grain-growth behaviors (Fig. 4 d-f). NG Ni undergoes abnormal grain growth from 36 nm to 142 nm ( \(\:\text{d}/{\text{d}}_{\text{0}}\) ≈ 3.9, Fig. 4 g), while NG Ni-Ti coarsens from 24 nm to 173 nm ( \(\:\text{d}/{\text{d}}_{\text{0}}\) ≈ 7.2). By contrast, G-UFG Ni-Ti shows negligible grain growth with the compressed micro-pillar averaging 150 nm ( \(\:\text{d}/{\text{d}}_{\text{0}}\) ≈ 0.9). To isolate thermal effects, all samples were annealed at 800 ℃ for 3 h. Inverse pole figures (Fig. 4 h-j) show catastrophic grain growth in NG Ni (36 nm → 119 µm, \(\:\text{d}/{\text{d}}_{\text{0}}\) > 3300). In NG Ni-Ti, \(\:\text{d}/{\text{d}}_{\text{0}}\) reaches ~ 13. G-UFG Ni-Ti shows the highest thermal stability \(\:\text{d}/{\text{d}}_{\text{0}}\) ≈ 2.7). This stability directly translates to retained mechanical properties. Correspondingly, the hardness of NG Ni dramatically drops from 436 Hv to 108 Hv, while G-UFG Ni-Ti experienced mild hardness drop from 470 Hv to 316 Hv (Supplementary Fig. 6). The gradient nanograin distribution near Ti particles is preserved after micro-pillar compression but homogenizes after 800°C annealing (Supplementary Fig. 7), delineating the boundaries of its stability regime. Discussion The exceptional, temperature-insensitive wear resistance of G-UFG Ni–Ti arises from two synergistic factors: a structurally stable UFG matrix that resists coarsening under long-cycle tribological and thermal loading, and dispersive internal gradient nanograined Ni/Ti interfaces that effectively suppress strain localization during repeated sliding. These two factors are discussed below. First, the exceptional wear resistance of the G-UFG heterostructure at both room and elevated temperatures is fundamentally governed by its superior structural stability. During sliding, grain boundaries migrate under the combined effects of accumulated tribo-induced plastic strain and thermal exposure 21 , promoting grain growth. The driving force for grain growth scales with γ/d 0 , where γ denotes the grain boundary energy and d 0 is the initial grain size. Since γ (~ 0.6 J m⁻²) is similar across all Ni samples, this driving force increases as grain size decreases, lowering the onset temperature for grain coarsening in nanograined structures 54 . This explains our experimental observation: the larger initial grain size of the UFG matrix in G-UFG Ni-Ti inherently presents a lower driving force for coarsening, which is quantitatively reflected in the smaller \(\:\text{d}/{\text{d}}_{\text{0}}\) values measured in the DRX layer after both wear and annealing. Under reciprocating sliding, the UFG matrix approaches a dynamic microstructural equilibrium state, in which dislocation multiplication is balanced by grain boundary migration and dislocation annihilation 55 , further enhancing thermal and mechanical stability. Moreover, diffusion across heterogeneous Ni/Ti interfaces remains sluggish due to the limited solid solubility of Ti in Ni (<0.1 at% at 25 ℃, ~ 10 at% at 800 ℃) and the high density of Ti particles constrains grain boundary motion in the Ni matrix 56 . This stabilized subsurface microstructure provides robust load-bearing support, suppresses the formation of delaminating tribolayer, and ultimately enhances wear resistance. Second, the mitigation of strain localization at GNG Ni/Ti interfaces further contributes to superior tribological performance. Strain accumulation is relieved through efficient strain transfer driven by the yield-stress gradient from NG to UFG regions 57 . This mechanism is directly evidenced by our micropillar compression tests: G-UFG Ni–Ti deforms homogeneously, whereas NG Ni–Ti exhibits pronounced localization and interfacial cracking. Unlike previously reported sub-millimeter-thick gradient nanograined surface layer, where the protective effect diminishes upon wear-off of the topmost nanograins 40 , G-UFG Ni–Ti embeds dispersive micrometer-scale GNG domains throughout the bulk, continuously suppressing strain localization during long-cycle sliding. Additionally, the intrinsic deformability of the Ti particles themselves plays a crucial role. Unlike brittle ceramic reinforcements such as Al 2 O 3 58 and WC 26 , which generates severe stress concentrations and interfacial cracking due to mechanical incompatibility, the deformable Ni/Ti interfaces maintain mechanical continuity and mitigate damage under tribological loading. Notably, the G-UFG strategy via microscale particle incorporation during direct-current electrodeposition extends beyond Ni-Ti. We have successfully demonstrated its applicability in other material systems, such as Ni–Ta and Ni–Nb (Supplementary Fig. 8). Its effectiveness relies on three key principles: (i) limited miscibility across the service-temperature range; (ii) a high density of dispersive internal gradients over a few micrometers, controlled by carefully tailoring the particle volume fraction; and (iii) sufficient intrinsic deformability of the introduced particles. Collectively, this strategy offers a generalizable design paradigm for designing advanced engineering materials with superior structural stability and sustained tribological performance. Conclusions To address the long-standing wear resistance dilemma of nanograined metals, we develop a G-UFG architecture featuring dispersive internal grain-size gradients embedded within a stable UFG matrix, fabricated by direct-current electrodeposition, which is an industrial scalable process at low cost. This heterostructure design exhibits unprecedented wear resistance across a wide temperature range of 25–800°C. The exceptional, temperature-insensitive wear resistance arises from a synergistic gradient architecture that stabilizes the ultrafine-grained matrix while delocalizing shear at GNG interfaces. By embedding gradients throughout the bulk rather than confining them to the surface, the architecture maintains continuous protection under long-cycle tribological loading. Beyond alleviating the intrinsic weaknesses of homogeneous nanograined metals, this strategy establishes generalizable design principle for durable, wear-resistant materials for operation in harsh environments. Methods Materials preparation NG Ni, NG Ni-Ti and G-UFG Ni-Ti samples, with the dimensions of 10 mm × 10 mm × 0.7 mm, were fabricated by direct current electrodeposition. The electrolyte solution was composed of NiSO 4 ·6H 2 O (240–300 g/L), NiCl 2 ·6H 2 O (40–50 g/L), boric acid (30–40 g/L), C 12 H 25 NaO 4 S (0.1–0.2 g/L), sodium saccharin (0–5 g/L) and Ti particle (0-200 g/L). The pH and temperature were maintained at 3.6 ± 0.2 and 50 ± 2°C, respectively. The cathode was a commercial pure Ti sheet with the dimensions of 10 mm × 10 mm × 2 mm. The current density was set as 50 ± 5 mA/cm 2 . The electrolyte bath containing Ti particles was subjected to magnetic stirring for 12 h before the deposition process to ensure better dispersion. The volume fraction of Ti particles rises from 0% to 19% with increasing concentration from 0 g/L to 200 g/L. The Ni-x%Ti (x = 4, 6, 11 and 19) samples are labeled by the volume fraction of Ti particles (Supplementary Fig. 9). Ni-11%Ti and Ni-19%Ti correspond to G-UFG Ni-Ti and NG Ni-Ti, respectively. Annealed specimens were cut into plates and then heated at 800°C for 3 hours followed by furnace cooling. Structural characterization The specimens for microstructure characterization were mechanically polished and then electropolished using an electrolyte composed of 10% perchloric acid and 90% alcohol with a voltage of 20 V at room temperature. As-deposited in-plane microstructures of Ni and Ni-Ti were characterized by a scanning electron microscope (SEM, FEI Quanta 250 F) operated at 20 kV and a transmission electron microscopy (TEM, FEI Titan G2 60–300) operated at 300 kV. The as-deposited TEM samples were removed from the Ti substrate and mechanically polished to a thickness of 20 µm, subsequently milled by ion beam at 173 K (Gatan 691). The specimens annealed at 800°C were characterized by a SEM (Zeiss Auriga) equipped with an EBSD system (Oxford Aztec 2.0). The morphologies of wear scars were characterized by a SEM with an Oxford energy dispersive X-ray spectrometer (EDS). The subsurface TEM specimens subjected to reciprocating sliding were cut by the focused ion beam (FIB) in the Zeiss Auriga dual-beam system. Before the FIB cutting process, Pt layers were deposited on the worn surface in order to protect it from ion beam damage. Cross-sectional microstructures of the compressed micro-pillars were characterized by transmission Kikuchi diffraction (TKD) in SEM. Mechanical characterization Hardness was measured at room temperature on a hardness tester (Shimadzu, HMV-G 21DT) using a Vickers diamond pyramidal indenter with an applied load of 2.92 N and a duration time of 10 s, averaging at least ten measurements per sample. Dry sliding wear tests at room temperature and elevated temperatures (400 ℃, 600 ℃ and 800 ℃) were carried out on a tribometer (Bruker, UMT-Ⅱ) and a high-temperature tribometer (Kaihua, GF-Ⅰ), respectively. Al 2 O 3 balls, 6 mm in diameter, were used in the ball-on-flat contact configuration. A normal load of 10 N, combined with a sliding velocity of 8 mm/s and a sliding stroke of 2 mm, was applied in the wear tests. For each sample, three wear scars were tested on a single specimen to ensure data repeatability. The coefficient of friction (COF) value (µ) was obtained from µ= F / P , where F is the frictional force measured by the tester, and P is the normal applied load. The wear rate was calculated using K = V /( P × S ), where V is the wear volume loss measured by a confocal laser scanning microscope (CLSM, OLS4000), S is the total sliding distance, and P is the normal load. The micro-pillars with a diameter of 4 µm and a height of 10 µm for compression tests were fabricated from the as-deposited samples via FIB. The height direction of the micro-pillars is parallel to the thickness direction. The taper angle of each pillar was kept below 2° in order to avoid overestimation of strength. The compression tests were performed using a nano-indentation system (FT-NMT04) with a diamond punch in a displacement-control mode at a strain rate of 5⋅10 − 4 s − 1 . The compression strain was set as 25%. Each compression experiment was conducted at least 4 times to ensure repeatability. Declarations Data and materials availability All data generated or analyzed during this study are included in this article (and its supplementary information files). Competing interests: Authors declare that they have no competing interests. Author contributions: X.C. supervised and conceived the project. Z.C. designed the project and analyzed the data. X.B. performed tribological tests and analyzed the data. F.L. analyzed the data, performed TEM measurements and wrote the draft manuscript. Y. L. and Y. Z. analyzed the data. X.C. wrote the manuscript with input from all authors. Acknowledgments The authors would like to acknowledge financial supports from National Natural Science Foundation of China (Grant No. 92366201, 52371068 and 52301157), Fundamental Research Funds for the Central Universities (Grant No. 30924010827 and 2025201004) and the open research fund of Suzhou Laboratory (No. SZLAB-1108-2024-TS002). The authors also want to acknowledge the support of the Jiangsu Key Laboratory of Advanced Micro-Nano Materials and Technology. SEM and TEM experiments are performed at the Materials Characterization and Research Center of Nanjing University of Science and Technology. References Mo YF (2009) Turner & I. Szlufarska, Friction laws at the nanoscale. Nature 457:1116–1119 Wang Y et al (2019) Triboemission of hydrocarbon molecules from diamond-like carbon friction interface induces atomic-scale wear. Sci Adv 5:eaax9301 Huang SQ et al (2025) Frictional strength regulated by roughness alignment. 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Scripta Mater 220:114895 Yu K et al (2026) Achieving excellent wear resistance in NbTiTa medium-entropy alloy self-lubricating composites at high-temperature via nano-Al 2 O 3 reinforcement. J Mater Sci Technol 247:14–28 Additional Declarations There is NO Competing Interest. Supplementary Files NiTiSupplementarymaterialsFinal.docx Supplymentary inforamtion Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-9233027","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":623775406,"identity":"a39ed0ff-9d7f-4f84-a2cb-075b8b013282","order_by":0,"name":"Xiang Chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBElEQVRIie3RIWvDQBTA8VcOLubg7Dsy2Fc4KKSb6WdJCFSlM4UwUUIhEDWordiH2EwmFwikqq2NmNhM1ETEKJXNNWvdJZOD3t/cO7gfJx6AyfQfI+3hNlMG2F7kXwl1FcF+AhfCTi/7iVyT6usHxg/cftp/3idRBFacIsw/tETEdDS8AX8mnjdvUiQ5AitChKLSEk7AsREy76WcpiiSDAEDBweLXEsosfYn8l4GVUMihNvvbsIJc0StfsGANoQ0v7BuImIW2iB9b1VOHMRtLhI2md25hZ7I3ToVh8ext1z5lY1hxLmVv5b1XE9UhP0ugqilUDW5nQBgcDgPdc9Lk8lkus6OOldIPtbIWjkAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-4802-9684","institution":"Nanjing University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Xiang","middleName":"","lastName":"Chen","suffix":""},{"id":623775408,"identity":"62106253-3160-402e-a0db-90e8b277ee7e","order_by":1,"name":"Zhaoshuo Chen","email":"","orcid":"","institution":"Nanjing University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Zhaoshuo","middleName":"","lastName":"Chen","suffix":""},{"id":623775410,"identity":"32dc8508-a02a-441e-8f5b-5890de0fb924","order_by":2,"name":"Xianzhi Bian","email":"","orcid":"","institution":"Nanjing University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Xianzhi","middleName":"","lastName":"Bian","suffix":""},{"id":623775412,"identity":"b6e56f8d-dcc5-44de-b151-19238beb7e12","order_by":3,"name":"Yan Lin","email":"","orcid":"","institution":"Nanjing University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Yan","middleName":"","lastName":"Lin","suffix":""},{"id":623775414,"identity":"e99ecbe4-0493-49f4-bc2f-8fa5764d046a","order_by":4,"name":"Fei Liang","email":"","orcid":"","institution":"Nanjing University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Fei","middleName":"","lastName":"Liang","suffix":""},{"id":623775416,"identity":"3c509e8e-2666-4f55-886f-c2e8a7c960d1","order_by":5,"name":"Yuntian Zhu","email":"","orcid":"","institution":"City University of Hong Kong","correspondingAuthor":false,"prefix":"","firstName":"Yuntian","middleName":"","lastName":"Zhu","suffix":""}],"badges":[],"createdAt":"2026-03-26 10:42:34","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9233027/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9233027/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108074155,"identity":"aae5dca6-b008-4a50-bf19-d5f8d0be06d4","added_by":"auto","created_at":"2026-04-29 06:26:50","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":478955,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eBreaking the wear resistance dilemma of nanograined metals with dispersive internal gradient heterostructure. \u003c/strong\u003eSchematics illustrating subsurface microstructure evolution under sliding at room temperature (RT) and high temperature (HT) for (\u003cstrong\u003ea\u003c/strong\u003e) NG and (\u003cstrong\u003eb\u003c/strong\u003e) G-UFG structures. NG structures exhibit grain-boundary brittleness, strain localization, and poor structural stability, leading to rapid wear. In contrast, G-UFG structures feature dispersive internal gradient nanograins around Ti particles, which stabilize the ultrafine-grained matrix and delocalize shear at GNG interfaces, enabling sustained low wear across a wide temperature range.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-9233027/v1/f29e3c159f2df593760d35fa.png"},{"id":108074167,"identity":"093bf65e-3b2e-4f87-959d-2ac339a49a15","added_by":"auto","created_at":"2026-04-29 06:26:53","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1296824,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMicrostructure and tribological properties of NG Ni, NG Ni-Ti and G-UFG Ni-Ti.\u003c/strong\u003e \u003cstrong\u003ea-c\u003c/strong\u003e, In-plane TEM images depict the (\u003cstrong\u003ea\u003c/strong\u003e) uniform nanograins in pure Ni, (\u003cstrong\u003eb\u003c/strong\u003e) uniform nanograins plus Ti particles in NG Ni-Ti and (\u003cstrong\u003ec\u003c/strong\u003e) gradient ultrafine grains around Ti particles in G-UFG Ni-Ti. \u003cstrong\u003ed\u003c/strong\u003e, TKD mapping of the gradient nanograined Ni between adjacent Ti particles in \u003cstrong\u003ec\u003c/strong\u003e. \u003cstrong\u003ee\u003c/strong\u003e, Grain size distribution versus distance for NG Ni, NG Ni-Ti and G-UFG Ni-Ti, where the solid points indicate Ti particle locations. \u003cstrong\u003ef\u003c/strong\u003e, Average COF value versus temperature. \u003cstrong\u003eg\u003c/strong\u003e, Representative cross-sectional wear profiles at 25 ℃ and 800 ℃. \u003cstrong\u003eh\u003c/strong\u003e, Wear rate versus temperature. \u003cstrong\u003ei\u003c/strong\u003e, Comparison of the COF and wear rate of our G-UFG Ni-Ti at RT with literature data of NG Ni and Ni-based composites \u003csup\u003e41-48\u003c/sup\u003e. \u003cstrong\u003ej\u003c/strong\u003e, Comparison of high-temperature wear rates of our G-UFG Ni-Ti with literature data of NG Ni \u003csup\u003e49\u003c/sup\u003e and NG binary Ni-based alloys \u003csup\u003e50-53\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-9233027/v1/bf18dafd2d20e6dd0e1dba91.png"},{"id":108074153,"identity":"b3a26339-5ed1-4076-9e34-42b55b54b4a0","added_by":"auto","created_at":"2026-04-29 06:26:49","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":694563,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTribo-induced microstructure evolution of NG Ni, NG Ni-Ti and G-UFG Ni-Ti at RT (25 ℃) and HT (800 ℃).\u003c/strong\u003e \u003cstrong\u003ea-c\u003c/strong\u003e, Typical cross-sectional TEM images of the subsurface region in (\u003cstrong\u003ea\u003c/strong\u003e) NG Ni, (\u003cstrong\u003eb\u003c/strong\u003e) NG Ni-Ti and (\u003cstrong\u003ec\u003c/strong\u003e) G-UFG Ni-Ti worn at 25 ℃. \u003cstrong\u003ed-f\u003c/strong\u003e, Typical cross-sectional TEM images of the subsurface region in (\u003cstrong\u003ed\u003c/strong\u003e) NG Ni, (\u003cstrong\u003ee\u003c/strong\u003e) NG Ni-Ti and (\u003cstrong\u003ef\u003c/strong\u003e) G-UFG Ni-Ti worn at 800 ℃. \u003cstrong\u003eg\u003c/strong\u003e,\u003cstrong\u003eh\u003c/strong\u003e, Variation of \u003cem\u003ed⁄d\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e \u0026nbsp;value along the distance to surface for the NG Ni, NG Ni-Ti and G-UFG Ni-Ti worn at (\u003cstrong\u003eg\u003c/strong\u003e) 25 ℃ and (\u003cstrong\u003eh\u003c/strong\u003e) 800 ℃.\u003c/p\u003e","description":"","filename":"image3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9233027/v1/32f2f193f548911fa93286aa.jpeg"},{"id":108074161,"identity":"abcaf986-de17-47c3-9fd4-95b9ab8a91a3","added_by":"auto","created_at":"2026-04-29 06:26:51","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":901890,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMicro-pillar compression and HT-annealing experiments for NG Ni, NG Ni-Ti and G-UFG Ni-Ti.\u003c/strong\u003e \u003cstrong\u003ea-c\u003c/strong\u003e, SEM images of micro-pillars for (\u003cstrong\u003ea\u003c/strong\u003e) NG Ni, (\u003cstrong\u003eb\u003c/strong\u003e) NG Ni-Ti and (\u003cstrong\u003ec\u003c/strong\u003e) G-UFG Ni-Ti before and after compression. \u003cstrong\u003ed-g\u003c/strong\u003e, Inverse pole figures of compressed micro-pillars for (\u003cstrong\u003ed\u003c/strong\u003e) NG Ni, (\u003cstrong\u003ee\u003c/strong\u003e) NG Ni-Ti and (\u003cstrong\u003ef\u003c/strong\u003e) G-UFG Ni-Ti, combined with (\u003cstrong\u003eg\u003c/strong\u003e) \u003cem\u003ed⁄d\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e values of as-deposited and compressed states. \u003cstrong\u003eh-k\u003c/strong\u003e, Inverse pole figures of the microstructure in (\u003cstrong\u003eh\u003c/strong\u003e) NG Ni, (\u003cstrong\u003ei\u003c/strong\u003e) NG Ni-Ti and (\u003cstrong\u003ej\u003c/strong\u003e) G-UFG Ni-Ti annealed at 800 ℃, combined with (\u003cstrong\u003ek\u003c/strong\u003e) \u003cem\u003ed⁄d\u003c/em\u003e\u003csub\u003e0 \u003c/sub\u003evalues of as-deposited and annealed states.\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9233027/v1/3dca8eb98006f04abe5b4315.jpeg"},{"id":108181860,"identity":"ddbff264-e16c-49ce-98b6-7d5418dee664","added_by":"auto","created_at":"2026-04-30 08:58:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3669296,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9233027/v1/3040af5d-a612-48d2-a889-2d2b9029a3e8.pdf"},{"id":108074156,"identity":"cab3ecfe-ddcb-48f5-a93f-785dc0181c4b","added_by":"auto","created_at":"2026-04-29 06:26:50","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":10770849,"visible":true,"origin":"","legend":"Supplymentary inforamtion","description":"","filename":"NiTiSupplementarymaterialsFinal.docx","url":"https://assets-eu.researchsquare.com/files/rs-9233027/v1/f4b71de43060747addb96c12.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Breaking the wear resistance dilemma of nanograined metals with dispersive internal gradient heterostructure","fulltext":[{"header":"Introduction","content":"\u003cp\u003eFriction and wear are pervasive sources of energy dissipation and material degradation at contacting interfaces \u003csup\u003e\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e, critically limiting the efficiency and service life of engineering systems from heavy-load gears to mining and rolling machinery. Minimizing friction and wear is therefore essential for both energy efficiency and operational reliability \u003csup\u003e\u003cspan additionalcitationids=\"CR8 CR9 CR10 CR11 CR12 CR13\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Conventional strategies to improve tribological performance primarily involve interfacial lubrication \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e and surface hardening \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. However, lubrication often fails under harsh environments, particularly at elevated temperatures \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Surface hardening through second-phase particle reinforcement \u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e or nanoscale grain refinement \u003csup\u003e\u003cspan additionalcitationids=\"CR22 CR23 CR24\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e, faces significant challenges in achieving long-term stability. In particle-reinforced materials, excessive mechanical incompatibility at matrix/particle interfaces can trigger interfacial cracking, leading to severe delamination during sliding \u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e. These limitations underscore the urgent need for innovative microstructural design strategies that combine high strength with sustained wear resistance under extreme conditions.\u003c/p\u003e \u003cp\u003eWhile nanograined (NG) metals are celebrated for their remarkable strength and hardness, their tribological performance remains a major issue in harsh environments. At ambient temperatures, NG metals exhibit high friction coefficients (0.6\u0026ndash;0.8) and elevated wear rates (~\u0026thinsp;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m)) under high-load sliding, primarily due to strain localization at grain boundaries \u003csup\u003e\u003cspan additionalcitationids=\"CR28\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. This results in brittleness and surface delamination, which represents an intrinsic \u0026ldquo;Achilles\u0026rsquo; heel\u0026rdquo; of NG metals \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. At elevated temperatures, the hurdle is exacerbated by grain coarsening \u003csup\u003e\u003cspan additionalcitationids=\"CR33\" citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e, which compromises their structural integrity and further diminishes wear resistance (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). Together, strain localization and structural instability constitute a long-standing wear-resistance dilemma for NG metals.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eGradient nanograined (GNG) surface layers with submillimeter thickness have emerged as a promising strategy to mitigate strain localization by introducing spatial variations in grain size and strength \u003csup\u003e\u003cspan additionalcitationids=\"CR36 CR37\" citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. By matching local yield stresses to the applied tribological stresses, such surface gradients can reduce friction and wear at room temperature \u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. However, maintaining low friction and wear under repeated sliding\u0026mdash;particularly at elevated temperatures\u0026mdash;remains a formidable challenge. Progressive removal of topmost nanograined layer, coupled with grain coarsening and renewed strain localization at nanograin interfaces, often leads to a rapid transition from low to high friction (~\u0026thinsp;0.3\u0026rarr;0.8) and accelerated material loss to ~\u0026thinsp;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m)) \u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. Critically, sustained low friction and wear across a broad temperature range has yet to be demonstrated.\u003c/p\u003e \u003cp\u003eTo address these limitations, we engineered dispersive, internally distributed gradient nanograined domains within an ultrafine-grained (UFG) pure Ni matrix by incorporating micro-scale Ti particles. Owing to the limited miscibility of the Ni-Ti binary system, the Ti particles effectively stabilize the Ni microstructure and create pronounced grain size gradients embedded throughout the bulk, extending over micrometer length scales. Unlike surface-confined gradient layers, which fail as the topmost nanograins are progressively removed during sliding, dispersive internal gradients remain active throughout the contacting volume, suppressing grain coarsening and mitigating strain localization at gradient interfaces under tribological loading (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). This heterostructure reduces wear rates by an order of magnitude from 25 to 800\u0026deg;C compared with homogeneous NG metals. Importantly, this gradient heterostructure concept is also demonstrated in Ni\u0026ndash;Ta and Ni\u0026ndash;Nb alloys, establishing a scalable, electrodeposition-compatible design paradigm for durable, high-performance metallic materials under harsh tribological environments.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eUsing direct-current electrodeposition, we fabricated three representative architectures: homogeneous NG Ni, NG Ni-Ti, and gradient UFG (G-UFG) Ni-Ti. The NG Ni deposit exhibits uniform nanograined structure with an average grain size of ~\u0026thinsp;53 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). Incorporation of micro-scale Ti particles serve as heterogeneous nucleation sites, refining the surrounding Ni matrix and producing smaller grains near the particles. In NG Ni-Ti, a high density of Ti particles generates uniform nanograins between adjacent particles, with an average grain size of 24 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). In contrast, G-UFG Ni-Ti displays pronounced internal gradient nanograined structure surrounding the Ti particles, as revealed by transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD) taken from the same region (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec,d), with grain sizes increasing from nanocrystalline near Ti particles to ultrafine grains with distance. Quantitative analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee) reveals that the Ni grain size between neighboring Ti particles spans\u0026thinsp;~\u0026thinsp;23\u0026ndash;244 nm. This gradient is confined to a localized region spanning\u0026thinsp;~\u0026thinsp;2\u0026ndash;3 \u0026micro;m while the matrix retains a predominantly UFG structure (Supplementary Fig.\u0026nbsp;1).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eReciprocating sliding tests across 25\u0026ndash;800\u0026deg;C reveal the superiority of the G-UFG architecture. For NG Ni, the coefficient of friction (COF) rises sharply from ~\u0026thinsp;0.29 at 25 ℃ to ~\u0026thinsp;0.55 at 600 ℃ and subsequently decreases to ~\u0026thinsp;0.46 at 800 ℃. For NG Ni-Ti, the COF basically fluctuates between 0.36 and 0.38, while G-UFG Ni-Ti increases gradually from 0.31 to 0.41 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef). At both 25\u0026deg;C and 800\u0026deg;C, wear scars are narrow and shallow in G-UFG Ni-Ti, contrasting with deep scars in NG Ni and NG Ni-Ti (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eg). Correspondingly, wear rates of NG Ni increases by two orders of magnitude, from ~\u0026thinsp;2.14\u0026sdot;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m) at 25 ℃ to ~\u0026thinsp;3.29\u0026sdot;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m) at 800 ℃. NG Ni-Ti increases moderately from ~\u0026thinsp;9.95\u0026sdot;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m) at 25 ℃ to ~\u0026thinsp;4.55\u0026sdot;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m) at 800 ℃. In contrast, G-UFG Ni-Ti maintains the lowest wear rates across the entire temperature range, from 1.74\u0026sdot;10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m) to 2.12\u0026sdot;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eh). Compared with NG metals exhibiting widely scatted wear rates spanning from 10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e to 10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m) \u003csup\u003e41\u0026ndash;48\u003c/sup\u003e, the G-UFG structure achieves both a low COF (~\u0026thinsp;0.3) and a substantially reduced wear rate (~\u0026thinsp;1.7\u0026sdot;10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e/(N\u0026middot;m)) at room temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ei). Across 25\u0026ndash;800\u0026deg;C, the G-UFG structure consistently outperforms NG Ni \u003csup\u003e49\u003c/sup\u003e and Ni-based alloys \u003csup\u003e\u003cspan additionalcitationids=\"CR51 CR52\" citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e, reducing wear rates by approximately an order of magnitude (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ej).\u003c/p\u003e \u003cp\u003eTo elucidate the microstructural origins of the superior wear resistance of the G-UFG architecture, we examined subsurface regions of NG Ni, NG Ni-Ti and G-UFG Ni-Ti after sliding at 25 ℃ and 800 ℃. After 25 ℃ sliding, NG Ni develops a two-layer subsurface structure (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea): a thick tribolayer (~\u0026thinsp;2 \u0026micro;m) of NiO nanograins with an average grain size of ~\u0026thinsp;12 nm (Supplementary Fig.\u0026nbsp;2), and an adjacent dynamic recrystallization (DRX) layer with coarsened grains (~\u0026thinsp;250\u0026ndash;300 nm). Massive cracks are identified within the brittle tribolayer and along the tribolayer/DRX interface. NG Ni-Ti exhibits a similar layered configuration (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb), consisting of a topmost NG tribolayer containing NiO and TiO\u003csub\u003e2\u003c/sub\u003e atop a DRX layer (Supplementary Fig.\u0026nbsp;2). Multiple microcracks nucleate and propagate within the tribolayer. In contrast, G-UFG Ni-Ti displays a tribolayer, a DRX layer and an undeformed matrix (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). Notably, the original Ti particles severely deform and transform from irregular blocks to thin lamellae, with minimum thicknesses of ~\u0026thinsp;23 nm and lengths exceeding 5 \u0026micro;m, as confirmed by EDS mapping in Supplementary Fig.\u0026nbsp;3.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eEven after sliding at 800 ℃, the G-UFG architecture maintains exceptional structural intergrity. NG Ni develops a tribolayer (~\u0026thinsp;6 \u0026micro;m thick) composed of equiaxed NiO nanograins, within which microcracks are prevalent (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed and Supplementary Fig.\u0026nbsp;4). Similarly, pronounced microcracks persist in the nanostructured tribolayer containing NiO and TiO\u003csub\u003e2\u003c/sub\u003e in NG Ni-Ti (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee and Supplementary Fig.\u0026nbsp;4). In contrast, G-UFG Ni-Ti retains a stable three-layer subsurface architecture comprising a thin, crack-free tribolayer, an underlying DRX layer and an undeformed matrix (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef). We quantified microstructural stability by analyzing grain growth in the DRX layer using the ratio \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e, where \u003cem\u003ed\u003c/em\u003e and \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e denote the DRX and original grain sizes, respectively. At 25 ℃, the \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e value for G-UFG Ni-Ti is only\u0026thinsp;~\u0026thinsp;1.46 (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg), compared with 4.96 of NG Ni and 2.23 of NG Ni-Ti. At 800 ℃, the \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e value in the DRX layer for G-UFG Ni-Ti is only\u0026thinsp;~\u0026thinsp;2.99, far lower than that of NG Ni (16.5) and NG Ni-Ti (36.45), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eh. Beyond ~\u0026thinsp;6 \u0026micro;m depth, the undeformed matrix retains its original grain size, demonstrating exceptional microstructural stability. Correspondingly, the worn surfaces of NG Ni and NG Ni-Ti exhibit severe peeling and delamination, whereas G-UFG Ni-Ti maintains smooth, intact wear scars at both 25\u0026deg;C and 800\u0026deg;C (Supplementary Fig.\u0026nbsp;5).\u003c/p\u003e \u003cp\u003eMicro-pillar compression and annealing experiments further confirm the superior stability of the dispersive internal gradient architecture (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Under uniaxial compression, NG Ni and G-UFG Ni-Ti both exhibit homogeneous deformation without local shear failure. In contrast, NG Ni-Ti develops a pronounced shear band along the Ni/Ti interface with several microcracks, indicating severe strain localization (see Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea-c). Subsurface microstructures (~\u0026thinsp;3 \u0026micro;m from pillar tops) reveal different grain-growth behaviors (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed-f). NG Ni undergoes abnormal grain growth from 36 nm to 142 nm (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e \u0026asymp; 3.9, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eg), while NG Ni-Ti coarsens from 24 nm to 173 nm (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e \u0026asymp; 7.2). By contrast, G-UFG Ni-Ti shows negligible grain growth with the compressed micro-pillar averaging 150 nm (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e \u0026asymp; 0.9). To isolate thermal effects, all samples were annealed at 800 ℃ for 3 h. Inverse pole figures (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eh-j) show catastrophic grain growth in NG Ni (36 nm \u0026rarr; 119 \u0026micro;m, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e \u0026gt; 3300). In NG Ni-Ti, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e reaches ~\u0026thinsp;13. G-UFG Ni-Ti shows the highest thermal stability \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e \u0026asymp; 2.7). This stability directly translates to retained mechanical properties. Correspondingly, the hardness of NG Ni dramatically drops from 436 Hv to 108 Hv, while G-UFG Ni-Ti experienced mild hardness drop from 470 Hv to 316 Hv (Supplementary Fig.\u0026nbsp;6). The gradient nanograin distribution near Ti particles is preserved after micro-pillar compression but homogenizes after 800\u0026deg;C annealing (Supplementary Fig.\u0026nbsp;7), delineating the boundaries of its stability regime.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe exceptional, temperature-insensitive wear resistance of G-UFG Ni\u0026ndash;Ti arises from two synergistic factors: a structurally stable UFG matrix that resists coarsening under long-cycle tribological and thermal loading, and dispersive internal gradient nanograined Ni/Ti interfaces that effectively suppress strain localization during repeated sliding. These two factors are discussed below.\u003c/p\u003e \u003cp\u003eFirst, the exceptional wear resistance of the G-UFG heterostructure at both room and elevated temperatures is fundamentally governed by its superior structural stability. During sliding, grain boundaries migrate under the combined effects of accumulated tribo-induced plastic strain and thermal exposure \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e, promoting grain growth. The driving force for grain growth scales with γ/d\u003csub\u003e0\u003c/sub\u003e, where γ denotes the grain boundary energy and d\u003csub\u003e0\u003c/sub\u003e is the initial grain size. Since γ (~\u0026thinsp;0.6 J m⁻\u0026sup2;) is similar across all Ni samples, this driving force increases as grain size decreases, lowering the onset temperature for grain coarsening in nanograined structures \u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. This explains our experimental observation: the larger initial grain size of the UFG matrix in G-UFG Ni-Ti inherently presents a lower driving force for coarsening, which is quantitatively reflected in the smaller \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{d}/{\\text{d}}_{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e values measured in the DRX layer after both wear and annealing. Under reciprocating sliding, the UFG matrix approaches a dynamic microstructural equilibrium state, in which dislocation multiplication is balanced by grain boundary migration and dislocation annihilation \u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e, further enhancing thermal and mechanical stability. Moreover, diffusion across heterogeneous Ni/Ti interfaces remains sluggish due to the limited solid solubility of Ti in Ni (\u0026lt;0.1 at% at 25 ℃, ~\u0026thinsp;10 at% at 800 ℃) and the high density of Ti particles constrains grain boundary motion in the Ni matrix \u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e. This stabilized subsurface microstructure provides robust load-bearing support, suppresses the formation of delaminating tribolayer, and ultimately enhances wear resistance.\u003c/p\u003e \u003cp\u003eSecond, the mitigation of strain localization at GNG Ni/Ti interfaces further contributes to superior tribological performance. Strain accumulation is relieved through efficient strain transfer driven by the yield-stress gradient from NG to UFG regions \u003csup\u003e\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e\u003c/sup\u003e. This mechanism is directly evidenced by our micropillar compression tests: G-UFG Ni\u0026ndash;Ti deforms homogeneously, whereas NG Ni\u0026ndash;Ti exhibits pronounced localization and interfacial cracking. Unlike previously reported sub-millimeter-thick gradient nanograined surface layer, where the protective effect diminishes upon wear-off of the topmost nanograins \u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e, G-UFG Ni\u0026ndash;Ti embeds dispersive micrometer-scale GNG domains throughout the bulk, continuously suppressing strain localization during long-cycle sliding. Additionally, the intrinsic deformability of the Ti particles themselves plays a crucial role. Unlike brittle ceramic reinforcements such as Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e \u003csup\u003e58\u003c/sup\u003e and WC \u003csup\u003e26\u003c/sup\u003e, which generates severe stress concentrations and interfacial cracking due to mechanical incompatibility, the deformable Ni/Ti interfaces maintain mechanical continuity and mitigate damage under tribological loading.\u003c/p\u003e \u003cp\u003eNotably, the G-UFG strategy via microscale particle incorporation during direct-current electrodeposition extends beyond Ni-Ti. We have successfully demonstrated its applicability in other material systems, such as Ni\u0026ndash;Ta and Ni\u0026ndash;Nb (Supplementary Fig.\u0026nbsp;8). Its effectiveness relies on three key principles: (i) limited miscibility across the service-temperature range; (ii) a high density of dispersive internal gradients over a few micrometers, controlled by carefully tailoring the particle volume fraction; and (iii) sufficient intrinsic deformability of the introduced particles. Collectively, this strategy offers a generalizable design paradigm for designing advanced engineering materials with superior structural stability and sustained tribological performance.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eTo address the long-standing wear resistance dilemma of nanograined metals, we develop a G-UFG architecture featuring dispersive internal grain-size gradients embedded within a stable UFG matrix, fabricated by direct-current electrodeposition, which is an industrial scalable process at low cost. This heterostructure design exhibits unprecedented wear resistance across a wide temperature range of 25\u0026ndash;800\u0026deg;C. The exceptional, temperature-insensitive wear resistance arises from a synergistic gradient architecture that stabilizes the ultrafine-grained matrix while delocalizing shear at GNG interfaces. By embedding gradients throughout the bulk rather than confining them to the surface, the architecture maintains continuous protection under long-cycle tribological loading. Beyond alleviating the intrinsic weaknesses of homogeneous nanograined metals, this strategy establishes generalizable design principle for durable, wear-resistant materials for operation in harsh environments.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eMaterials preparation\u003c/h2\u003e \u003cp\u003eNG Ni, NG Ni-Ti and G-UFG Ni-Ti samples, with the dimensions of 10 mm \u0026times; 10 mm \u0026times; 0.7 mm, were fabricated by direct current electrodeposition. The electrolyte solution was composed of NiSO\u003csub\u003e4\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO (240\u0026ndash;300 g/L), NiCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO (40\u0026ndash;50 g/L), boric acid (30\u0026ndash;40 g/L), C\u003csub\u003e12\u003c/sub\u003eH\u003csub\u003e25\u003c/sub\u003eNaO\u003csub\u003e4\u003c/sub\u003eS (0.1\u0026ndash;0.2 g/L), sodium saccharin (0\u0026ndash;5 g/L) and Ti particle (0-200 g/L). The pH and temperature were maintained at 3.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 and 50\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C, respectively. The cathode was a commercial pure Ti sheet with the dimensions of 10 mm \u0026times; 10 mm \u0026times; 2 mm. The current density was set as 50\u0026thinsp;\u0026plusmn;\u0026thinsp;5 mA/cm\u003csup\u003e2\u003c/sup\u003e. The electrolyte bath containing Ti particles was subjected to magnetic stirring for 12 h before the deposition process to ensure better dispersion. The volume fraction of Ti particles rises from 0% to 19% with increasing concentration from 0 g/L to 200 g/L. The Ni-x%Ti (x\u0026thinsp;=\u0026thinsp;4, 6, 11 and 19) samples are labeled by the volume fraction of Ti particles (Supplementary Fig.\u0026nbsp;9). Ni-11%Ti and Ni-19%Ti correspond to G-UFG Ni-Ti and NG Ni-Ti, respectively. Annealed specimens were cut into plates and then heated at 800\u0026deg;C for 3 hours followed by furnace cooling.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStructural characterization\u003c/h3\u003e\n\u003cp\u003eThe specimens for microstructure characterization were mechanically polished and then electropolished using an electrolyte composed of 10% perchloric acid and 90% alcohol with a voltage of 20 V at room temperature. As-deposited in-plane microstructures of Ni and Ni-Ti were characterized by a scanning electron microscope (SEM, FEI Quanta 250 F) operated at 20 kV and a transmission electron microscopy (TEM, FEI Titan G2 60\u0026ndash;300) operated at 300 kV. The as-deposited TEM samples were removed from the Ti substrate and mechanically polished to a thickness of 20 \u0026micro;m, subsequently milled by ion beam at 173 K (Gatan 691). The specimens annealed at 800\u0026deg;C were characterized by a SEM (Zeiss Auriga) equipped with an EBSD system (Oxford Aztec 2.0). The morphologies of wear scars were characterized by a SEM with an Oxford energy dispersive X-ray spectrometer (EDS). The subsurface TEM specimens subjected to reciprocating sliding were cut by the focused ion beam (FIB) in the Zeiss Auriga dual-beam system. Before the FIB cutting process, Pt layers were deposited on the worn surface in order to protect it from ion beam damage. Cross-sectional microstructures of the compressed micro-pillars were characterized by transmission Kikuchi diffraction (TKD) in SEM.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eMechanical characterization\u003c/h2\u003e \u003cp\u003eHardness was measured at room temperature on a hardness tester (Shimadzu, HMV-G 21DT) using a Vickers diamond pyramidal indenter with an applied load of 2.92 N and a duration time of 10 s, averaging at least ten measurements per sample. Dry sliding wear tests at room temperature and elevated temperatures (400 ℃, 600 ℃ and 800 ℃) were carried out on a tribometer (Bruker, UMT-Ⅱ) and a high-temperature tribometer (Kaihua, GF-Ⅰ), respectively. Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e balls, 6 mm in diameter, were used in the ball-on-flat contact configuration. A normal load of 10 N, combined with a sliding velocity of 8 mm/s and a sliding stroke of 2 mm, was applied in the wear tests. For each sample, three wear scars were tested on a single specimen to ensure data repeatability. The coefficient of friction (COF) value (\u0026micro;) was obtained from \u0026micro;= \u003cem\u003eF\u003c/em\u003e/\u003cem\u003eP\u003c/em\u003e, where F is the frictional force measured by the tester, and P is the normal applied load. The wear rate was calculated using \u003cem\u003eK\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eV\u003c/em\u003e/(\u003cem\u003eP\u003c/em\u003e\u0026times;\u003cem\u003eS\u003c/em\u003e), where \u003cem\u003eV\u003c/em\u003e is the wear volume loss measured by a confocal laser scanning microscope (CLSM, OLS4000), \u003cem\u003eS\u003c/em\u003e is the total sliding distance, and \u003cem\u003eP\u003c/em\u003e is the normal load.\u003c/p\u003e \u003cp\u003eThe micro-pillars with a diameter of 4 \u0026micro;m and a height of 10 \u0026micro;m for compression tests were fabricated from the as-deposited samples via FIB. The height direction of the micro-pillars is parallel to the thickness direction. The taper angle of each pillar was kept below 2\u0026deg; in order to avoid overestimation of strength. The compression tests were performed using a nano-indentation system (FT-NMT04) with a diamond punch in a displacement-control mode at a strain rate of 5\u0026sdot;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The compression strain was set as 25%. Each compression experiment was conducted at least 4 times to ensure repeatability.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eData and materials availability\u003c/strong\u003e \u003cp\u003eAll data generated or analyzed during this study are included in this article (and its supplementary information files).\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests:\u003c/h2\u003e \u003cp\u003eAuthors declare that they have no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor contributions:\u003c/h2\u003e \u003cp\u003eX.C. supervised and conceived the project. Z.C. designed the project and analyzed the data. X.B. performed tribological tests and analyzed the data. F.L. analyzed the data, performed TEM measurements and wrote the draft manuscript. Y. L. and Y. Z. analyzed the data. X.C. wrote the manuscript with input from all authors.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eThe authors would like to acknowledge financial supports from National Natural Science Foundation of China (Grant No. 92366201, 52371068 and 52301157), Fundamental Research Funds for the Central Universities (Grant No. 30924010827 and 2025201004) and the open research fund of Suzhou Laboratory (No. SZLAB-1108-2024-TS002). The authors also want to acknowledge the support of the Jiangsu Key Laboratory of Advanced Micro-Nano Materials and Technology. SEM and TEM experiments are performed at the Materials Characterization and Research Center of Nanjing University of Science and Technology.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMo YF (2009) Turner \u0026amp; I. Szlufarska, Friction laws at the nanoscale. 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J Mater Sci Technol 247:14\u0026ndash;28\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-9233027/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9233027/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFriction and wear impose fundamental constraints on the reliability and lifetime of structural materials. Although nanograined (NG) metals with grain sizes below ~\u0026thinsp;100 nm exhibit exceptional strength and hardness, their wear resistance is intrinsically constrained by strain localization at ambient temperatures and pronounced grain coarsening at elevated temperatures. Here, we address this long-standing problem by introducing dispersive gradient nanograined domains into an ultrafine-grained pure nickel via micro-scale titanium incorporation. This internal gradient architecture reduces wear rates by an order of magnitude across a broad temperature range (25\u0026ndash;800\u0026deg;C) compared with homogeneous NG metals. The exceptional wear resistance arises from the combined thermal and mechanical stability of the ultrafine-grained matrix and the mitigation of strain localization at gradient interfaces. Compatible with scalable electrodeposition, this strategy establishes a broadly applicable materials design paradigm for achieving durable metallic surfaces under harsh tribological conditions.\u003c/p\u003e","manuscriptTitle":"Breaking the wear resistance dilemma of nanograined metals with dispersive internal gradient heterostructure","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-29 06:26:44","doi":"10.21203/rs.3.rs-9233027/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"9d4032ff-662a-49c3-8aa8-136b2f10e7e1","owner":[],"postedDate":"April 29th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"This content is not available.","date":"2026-05-11T12:36:26+00:00","index":2,"fulltext":"This content is not available."}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":66386800,"name":"Physical sciences/Materials science/Structural materials/Mechanical properties"},{"id":66386801,"name":"Physical sciences/Materials science/Structural materials/Metals and alloys"}],"tags":[],"updatedAt":"2026-04-29T06:26:44+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-29 06:26:44","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9233027","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9233027","identity":"rs-9233027","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}