Tunable and efficient electromagnetic interference shielding properties of Cu-Fe alloy prepared by powder metallurgy

Tunable and efficient electromagnetic interference shielding properties of Cu-Fe alloy prepared by powder metallurgy | 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 Research Article Tunable and efficient electromagnetic interference shielding properties of Cu-Fe alloy prepared by powder metallurgy Liang Zhou, MUHAIMINUL ISLAM SHAKIL, Yanrong Feng, Yaping Wang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9084786/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Microstructure, electrical conductivity, magnetic properties, and electromagnetic interference (EMI) shielding properties of hot-pressed and hot-rolled Cu-Fe alloys were investigated in this paper. The results show that the Cu-Fe alloys are Cu and magnetic α-Fe mixtures. As increasing Fe content, the electrical conductivity decreases significantly, while the saturation magnetic induction intensity and the coercivity present an evident increasing trend. The EMI shielding effectiveness (SE) of Cu-Fe alloy decreases gradually with increasing Fe content in low frequency, and the SE values present a significant downward trend as increasing the frequency in high frequency. Owing to the suitable conductivity and magnetic properties, the average SE value of Cu-20Fe alloy with 0.24mm thickness stabilizes at 109.7dB over the entire frequency range, indicating the tunable and efficient EMI shielding properties. The Cu-Fe alloys fabricated here could be qualified as an idea candidate for EMI shielding applications in the electronic and communication field. Cu-Fe alloys Conductivity Magnetic property Electromagnetic interference shielding Hot-pressing Hot-rolling Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1. Introduction With the rapid development of electronic information technology, excessive electromagnetic (EM) radiation produced by electronic devices and information transmission not only disrupts the normal operation of electronic equipment but also endangers human health [ 1 – 3 ] . Therefore, EM radiation pollution has become the fifth most prevalent pollution after air, water, noise, and solid waste [ 4 ] . To reduce the intensity of EM radiation to a safe range, EM shielding materials is an effective strategy to solve the problems caused by EM radiation pollution. Currently, many kinds of EM shielding materials have been studied, including metal, carbon, ceramic polymer, and composite materials [ 5 – 7 ] . Among them, metal and carbon are the main functional materials that provide shielding ability. Metal EM shielding materials such as Magnesium (Mg), Aluminum (Al), Copper (Cu) and their alloys with excellent electrical conductivity, suitable mechanical, low-cost, and high surface gloss have potential applications in the 3C products, automobiles, and aerospace fields. It’s worth noting that Copper alloys, also known as a traditional electronic packaging material, not only possesses good heat dispersion due to their high thermal conductivity, but also presents the favorable EM shielding properties caused by the high electrical conductivity, indicating their potential applications in 5G integrated high-power chips of 3C products [ 8 – 10 ] . Furthermore, the copper component contributes to enhance EMI shielding properties at high frequencies, while the addition of magnetic iron for Cu-based alloys improves the EMI shielding at low frequencies. Over the past decade, Cu-Fe alloys have been widely studied as EMI shielding materials to obtain the desired combination of the mechanical properties and electrical conductivity for the applications in the integrated circuits and electronic industries [ 11 ] . Wu et al. found that Cu-Fe alloys with higher Fe content exhibited higher strength and lower electrical conductivity, which are ascribed to the strengthening and electron scattering effects owing to the generation of dendritic structure [ 12 ] . Wang et al. demonstrated through experiments that the electrical conductivity and tensile strength of Cu-10Fe alloys prepared by multi-stage thermomechanical treatment process could reach 58% IACS and 608 MPa, respectively [ 13 ] . Compared with Cu metal, the less atomic scattering in Cu-10Fe alloys occurs due to the fewer vacancy and dislocation defects within the Cu matrix after aging, and thus the increased conductivity can be attributed to the precipitation of Fe atoms. In addition, the conductivity and mechanical properties can also be controlled by heat treatment under different temperatures. Qu et al. investigated the electrical conductivity of Cu-15Fe alloys annealed at different temperatures. The results revealed that an increase of filament spacing and reduction of interface area results in the increase of conductivity with increasing temperature below 500 o C, while the conductivity values represent a decreasing trend above 500 o C due to the rapidly increase of Fe solubility in Cu-matrix [ 14 ] . In the aspect of EMI shielding properties, Pang et al. prepared Cu-10Fe and Cu-10Fe-0.4Si alloys by melting and casting method and investigated the effect of Si on the properties of Cu-10Fe alloy [ 15 ] . As is well-known, Cu-Fe alloys filled with higher Fe content are beneficial for improving the EMI shielding properties in the low frequency regions, which are commonly emitted from 3C products in our dairy life. However, The traditional preparation methods, including in-situ production and rapid solidification, are difficult to produce Cu-Fe alloys with high Fe content due to the disadvantages of Cu(Fe)-rich phases and the segregation of Fe phase [ 16 – 19 ] . By comparation, the alloys prepared by powder metallurgy possesses the double advantages of uniform organization and fine grain size, as well as the easy and effective regulations of component content to eliminate composition segregation [ 20 , 21 ] . Reports on the microstructure and EMI shielding properties of Cu-Fe alloys with high Fe content fabricated by powder metallurgy process are very limited. In this study, Cu-Fe alloys with 20–50 wt.% Fe content were prepared by hot-pressed sintering followed by hot rolling. The microstructure, physical properties and EMI shielding properties were systematically investigated, and the possible EMI shielding mechanisms affected by electrical conductivity and magnetic property related to Fe content were also discussed. The Cu-Fe alloys fabricated here could be qualified as an idea candidate for EMI shielding applications in the fields of electronics and communication. 2. Experimental 2.1 Sample preparation Electrolytic copper powder with an average particle size of ~ 50 µm and high-purity iron powder with ~ 5 µm average diameter were used as raw materials. In the whole process, 20, 30, 40 and 50 wt.% iron powders were uniformly mixed with copper powders in a planetary ball mill for 4 h. The ratio of ball to powders was 6:1 and the rotation speed was 250 r/min in the ball milling process. Subsequently, the mixed powders after ball milling were vacuum hot-pressing sintered at 980°C for 2 h under a load of 45 MPa in a graphite mold with 40 mm diameter and 80 mm height. Finally, the sintered samples were hot rolled at 800°C followed by a polishing with sandpaper to remove the oxide layer, and the Cu-Fe alloy sheets with thickness of 0.24 mm were obtained. The whole preparation process is shown in Fig. 1 . 2.2 Characterization The density of the samples was tested via the Archimedean method [ 22 ] . The phase composition was measured by X-ray diffraction (XRD, Philips X 'pert MPD) in the 2θ range of 20 o -100 o with the use of Cu-Kα radiation. Scanning electron microscopy (SEM, Hitachi S-4800) was used to observe the microstructure of the samples, and the element distribution was performed by X-ray energy dispersive spectroscopy (EDS). The electrical conductivity of the samples with a dimension of 35 mm × 3 mm × 1 mm was tested with four-probe method at room temperature. The magnetic properties were determined by a vibrating sample magnetometer (Lakeshore-7400s), and the weight of the samples was controlled to be about 10 mg. For EMI shielding testing, the samples were processed into a thin metal disc with 133 mm diameter and 0.24 mm thickness, and the EMI shielding effectiveness were conducted by a DR-S03 coaxial shielding effectiveness testing device in the frequency range of 30 MHz − 1.5 GHz. The testing device is mainly composed of vector network analyzer, transmission line and coaxial flange components, and the schematic diagram is presented in Fig. 2 . 3. Results and discussion 3.1 Phase composition Cu-Fe alloys are usually composed of body-centered cubic (Bcc) α-Fe and Fcc-Cu phases [ 23 ] . Figure 3 shows the XRD patterns of the prepared Cu-Fe alloys with different Fe contents. As can be seen from Fig. 3 , the constituent phases of the alloys are Cu and α-Fe, indicating the existence of mixtures. The Cu phase presents obvious diffraction peaks at 43.3°, 50.4°, 74.1° and 89.9°, corresponding to crystallographic indices of (111), (200), (220) and (311), respectively [ 24 ] . The diffraction peak of α-Fe is strongest at 44.7°, and it corresponds to the (110) crystal plane index. With the increase of Fe content, the intensity of the Cu diffraction peaks gradually decreases, while that of the Fe diffraction peak at 44.7° presents an opposite trend. In addition, the shift of diffraction peaks for Cu and Fe phases has not been observed in the XRD patterns, demonstrating that the Cu-Fe alloys prepared here were not oxidized during the process of hot-pressed sintering. 3.2 Microstructure and EDS analysis The microstructure of Cu-Fe alloys with 20, 30, 40 and 50 wt.% Fe content is presented in Fig. 4 (a-d). According to the backscattered electron (BSE) images shown in Fig. 4 (a-d), the Cu-Fe alloys consist of primary α-Fe phases with dark region random distributed in the brightly colored Cu matrix, and Fe and Cu basically exist in the form of mixtures. The Fe phases with the size ranging from 5 to 40µm are elongated and irregular after the rolling process. Meanwhile, some micro-scaled pores, a typical characteristic of the samples fabricated by hot-pressed sintering, can be observed, appearing as black dots. In addition, with the increase of iron content, the distance between the iron phases evidently decreases, resulting in the formation of iron clusters for the Cu-Fe alloys with higher Fe content. Figure 4 (e) shows the microstructure and element distribution of hot-pressing sintered Cu-20Fe alloys followed by hot-rolling, which indicates the random distribution of Fe fillers and the existence of numerous Cu/Fe interfaces. It is worth noting that the Cu/Fe interfaces are beneficial for multiple scattering of incident electromagnetic waves, which effectively improve the EMI shielding properties. 3.3 Electrical conductivity and magnetic properties Figure 5 shows the electrical conductivity plots for Cu-Fe alloys with different Fe contents. It is clearly observed that the electrical conductivity decreases significantly with the increase of Fe content. Based on the above discussions in Fig. 3 , the Fe phase in Cu-Fe alloys exists in the form of magnetic α-Fe (Bcc), which effective scattering the conduction electrons in the electric field [ 25 , 26 ] . Furthermore, as increasing the Fe content, the orientation of large-angle grain boundary gradually increases, contributing to the higher resistivity [ 27 – 29 ] . In addition, the internal stress exists at the grain boundaries due to the much harder extrusion forming of Fe relative to Cu in the rolling process. Hence, more lattice strain is generated as Fe content increases, which also results in the decrease of electrical conductivity [ 30 ] . Therefore, the possibility scattering of the conduction electrons, the large-angle grain boundaries, and the lattice strain at the Cu/Fe interfaces leads to a significant decrease in the electrical conductivity of the investigated Cu-Fe alloys as increasing the Fe content. The hysteresis loops of Cu-Fe alloys with different Fe contents are presented in Fig. 6 . The results show that the saturation magnetic induction intensity increases with the increase of Fe content. After hot rolling, the Cu-Fe alloys is still composed of Fcc-Cu and magnetic Bcc-Fe. Each Fe atom has a complete magnetic moment, and every two Fe atoms are magnetically paired during the forming process. As increasing Fe content, the numbers of paired magnetic Fe atoms in Cu-Fe alloys increases, and the more clusters are prone to form. Thus, the Cu-50Fe alloy exhibits the highest value of saturation magnetic induction intensity due to its highest Fe content for our prepared Cu-Fe alloys in this study. Figure 7 exhibits the magnetic properties of Cu-Fe alloys with varying Fe contents. Figure 7 (a-b) reveals that the saturation magnetic induction (M s ) and remanent magnetization (M r ) of the Cu-Fe alloys increase with the increase of Fe content. It is worth mentioning that the M r values increase greatly for the Cu-Fe alloys with 30 wt.% to 40 wt.% Fe contents, which can be attributed to the transformation of soft magnetic and hard magnetic properties of the alloys. From Fig. 7 (c-d), it can be observed that the magnetic remanence ratio (M r /M s ) and coercivity (H c ) of the alloys increases more significantly as the Fe content increases from 30wt.% to 50wt.%. As everyone knows, the defects (such as dislocations and grain boundaries) and impurities suppress the electron spin and thus increase the coercivity [ 31 , 32 ] . With increasing the Fe content, the large angle grain boundaries orientation, and the degree of strain in Cu atoms increase. As a results, an increase in electron spin contributes to the increase of the coercivity for the studied Cu-Fe alloys. 3.3 Electromagnetic interference shielding effectiveness Figure 8 exhibits the EMI shielding effectiveness (SE) curves of Cu-Fe alloys with different Fe content. It can be clearly observed that the SE values gradually decrease with the increase of frequency. As shown in Fig. 8 , the SE values of Cu-Fe alloys with 20wt.% to 50 wt.% Fe contents are stable at above 100 dB in 30 ~ 400 MHz, and their high permeability and low reluctance characteristics play dominant roles in the favorable EMI shielding properties for the low-frequency range. It can be also observed that the SE values of Cu-Fe alloys exhibit a slightly decreasing trend with increasing the Fe content. As is known to all, the EMI shielding properties of the alloys are determined by the conductivity and magnetic properties. According to the discussion in Fig. 5 , the conductivity values are much higher for the alloys with lower Fe content, which contributes to the enhanced SE values. However, owing to the dominant role of the magnetic properties on the EMI shielding effectiveness in the low frequency as shown in Figs. 6 and 7 , no significant increase in the SE values can be observed in the low frequency range. Furthermore, the SE values present a significant downward trend as increasing the frequency from 400MHz to 1500MHz, especially for the Cu-30Fe, Cu-40Fe, and Cu-50Fe alloys. In the high-frequency range, the obvious decrease of SE values can be mainly attributed to the decrease of conductivity [ 3 , 33 ] , resulting in the decrease of the induced current. Significantly, the decrease of the induced current would lead to the decrease in the offset magnetic field, which furtherly reduces the magnetic loss of the EMI shielding material. Meanwhile, conductive carriers are generated on the surface of the alloys in a changing electromagnetic field, and the carriers will shift from disorder to order along with directional drift. Most notably, the directional drift of carrier can form conduction current, and the electromagnetic energy is dissipated in the form of heat, known as conductance loss. Therefore, for the investigated Cu-Fe alloys, the EMI shielding properties can be effective regulated by the electrical conductivity and magnetic properties, and the EMI shielding mechanisms of Cu-Fe alloys against incident electromagnetic wave are composed of reflection, absorption loss and conductance loss [ 34 , 35 ] , which is shown in Fig. 9 . In addition, it can be found that the Cu-40Fe alloy present a relatively much higher EMI shielding effeteness compared with the Cu-30Fe and Cu-40Fe alloys. As everyone knows, EMI shielding properties are significantly affected by the thickness of the testing samples, and Table 1 shows the parameters of the samples. Based on the discussion of Fig. 6 (a) and Table.1, the higher EMI shielding effeteness of Cu-40Fe alloy can be ascribed to the fact that its thickness is much higher than that of Cu-30Fe and Cu-50Fe samples. Based on the previous reports, the average SE value of Cu-10Fe with 1.0mm thickness is 104.6 dB in 30 MHz ~ 1.5 GHz [ 15 ] . By comparation, the average SE value of Cu-20Fe alloy with 0.24mm thickness stabilizes at 109.7dB over the entire frequency range, exhibiting the highest EMI shielding properties for our investigated Cu-Fe alloys. Table 1 Parameters of the testing samples Cu-Fe alloys Density (g/cm 3 ) Relative density (%) Thickness(mm) Cu-20Fe 8.55 98 0.24 Cu-30Fe 8.4676 98.1 0.26 Cu-40Fe 8.1739 95.9 0.34 Cu-50Fe 8.3483 99.4 0.30 To eliminate the effect of thickness and density on the EMI shielding effeteness, the specific shielding effectiveness (SSE) can be used to express the EMI shielding properties of the alloys, and the expression formula is presented as follows: $$\:SSE=\frac{SE}{\rho\:\times\:d}$$ 1 where SE (dB) represents the electromagnetic shielding effectiveness, ρ (g/cm 3 ) is the density, d (cm) is the thickness, and the units of SSE are dB.cm 2 .g − 1 . Figure 10 presents the SSE of Cu-Fe alloys with different Fe content. As shown in Fig. 10 , the SSE values of Cu-Fe alloys with 30, 40, and 50wt.% Fe contents exhibit a significant downward trend, which is mainly attributed to the decrease of electrical conductivity. By comparation, the H c values of Cu-40Fe and Cu-50Fe alloys tend to be stable, and thus no significant difference in SSE values can be observed. In conclusion, for the Cu-Fe alloys with 10–50 wt.% Fe contents based on this study and previous report, Cu-20Fe alloy in this study presents the highest EMI shielding properties, exhibiting the more favorable electromagnetic shielding performance, and its SSE value is stable at 542 dB.cm 2 .g − 1 in 30 MHz ~ 1.5 GHz. 4. Conclusions In this study, Cu-Fe alloys with different Fe contents were prepared by hot-pressed sintering followed by hot rolling. Microstructure, electrical conductivity, and magnetic properties were analyzed, and the electromagnetic interference (EMI) shielding properties were investigated in the frequency range of 30 MHz ~ 1.5 GHz. The results show that the Cu-Fe alloys are composed of Cu phase and magnetic α-Fe phase, existing in the form of mixtures. As increasing Fe content, the electrical conductivity decreases significantly, while the saturation magnetic induction intensity and the coercivity present an increasing trend. In addition, the EMI shielding properties of Cu-Fe alloy decreases gradually with the increase of Fe content in the low-frequency range, and the SE values present a significant downward trend as increasing the frequency in the high-frequency region. Owing to the suitable conductivity and magnetic properties, the average SE value of Cu-20Fe alloy with 0.24mm thickness stabilizes at 109.7dB over the entire frequency range, exhibiting the favorable EMI shielding properties for our investigated Cu-Fe alloys. The excellent EMI shielding properties were attributed to the reflection, absorption loss and conductance loss, and the Cu-Fe alloys fabricated here could be qualified as an idea candidate for EMI shielding applications in the fields of electronics and communication. Declarations Competing interest The authors have no relevant financial or non-financial interests to disclose. Ethical approval The authors declare that there are no potential conflicts of interest and that no part of this research involves human participants and/or animals. Author Contribution Liang Zhou, MUHAIMINUL ISLAM SHAKIL and Yanrong Feng wrote the main manuscript text, while Yaping Wang, Zhaorui Zhang and Fudong Nan prepared figures 1-10. All authors reviewed the manuscript. Acknowledgement This work was financially supported by Natural Science Foundation of Shaanxi Province (No. 2021JLM-41), Key Research and Development Program in Shaanxi Province of China (No. 2025CY-YBXM-128), and the Fundamental Research Funds for the Central Universities from Chang'an University (No. 300102313201). Data Availability All authors hereby declare that the data involved in this research are true. Moreover, such data will be provided as required. References Wu N, Hu Q, Wei R et al. Review on the electromagnetic interference shielding properties of carbon based materials and their novel composites: Recent progress, challenges and prospects. Carbon 2021; 176:88-105. Zachariah SM, Grohens Y, Kalarikkal N, Thomas S. Hybrid materials for electromagnetic shielding: A review. Polymer Composites 2022; 43:2507-2544. Zhao B, Hamidinejad M, Wang S et al. Advances in electromagnetic shielding properties of composite foams. 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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-9084786","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":608264863,"identity":"15a3d4fa-ca1b-48a9-b494-995199516b58","order_by":0,"name":"Liang 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Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Zhaorui","middleName":"","lastName":"Zhang","suffix":""},{"id":608264876,"identity":"5ff968dd-d87e-4494-96a2-1c208c78d466","order_by":5,"name":"Fudong Nan","email":"","orcid":"","institution":"Shaannxi Coal Chemical Industry Technology Research Instituted Co., Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Fudong","middleName":"","lastName":"Nan","suffix":""}],"badges":[],"createdAt":"2026-03-10 13:53:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9084786/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9084786/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105871789,"identity":"f2c14ed6-b7f4-4a56-b2d1-09a4d8f0b965","added_by":"auto","created_at":"2026-04-01 04:53:06","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":233836,"visible":true,"origin":"","legend":"\u003cp\u003eFlow chart of preparation of Cu-Fe alloys\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/649e209824d76242a299277a.png"},{"id":105871791,"identity":"5a6b4cf5-dfaf-418a-a0f1-450b06f1ed62","added_by":"auto","created_at":"2026-04-01 04:53:06","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":76903,"visible":true,"origin":"","legend":"\u003cp\u003eschematic diagram of electromagnetic shielding coaxial test method\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/773a9b219af176d0341a8fc2.png"},{"id":105871792,"identity":"87506e51-18a2-485a-be99-6edb0d1f8197","added_by":"auto","created_at":"2026-04-01 04:53:06","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":38376,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns of Cu-Fe alloys with different Fe contents\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/3d6181ced10e94f497c7f4db.png"},{"id":105871794,"identity":"28dc0fc7-398a-46a1-b0d7-32b7608e79c4","added_by":"auto","created_at":"2026-04-01 04:53:06","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":997146,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of Cu-Fe alloys with different (a) 20, (b) 30, (c) 40, and (d) 50 wt.% Fe contents, (e) EDS diagram of Cu-20Fe alloys\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/97af30c65c546fcea369859f.png"},{"id":105871790,"identity":"c67975cd-ad5c-4a7c-977b-7cbf24d0f2b7","added_by":"auto","created_at":"2026-04-01 04:53:06","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":5713,"visible":true,"origin":"","legend":"\u003cp\u003eElectrical conductivity of Cu-Fe alloys with different Fe content.\u003c/p\u003e","description":"","filename":"placeholderimageCopy.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/45dfc696f0a91483a8753a9a.png"},{"id":105905203,"identity":"b4e08e54-0b1e-4c10-bd21-cce6a5dae5f6","added_by":"auto","created_at":"2026-04-01 10:11:36","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":390797,"visible":true,"origin":"","legend":"\u003cp\u003eHysteresis line with Cu-Fe alloys with different Fe contents.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/96a58555f375d5ab7fe99ea1.png"},{"id":105871797,"identity":"b8533267-cf19-4275-aa09-5a16b5225f6e","added_by":"auto","created_at":"2026-04-01 04:53:06","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":250450,"visible":true,"origin":"","legend":"\u003cp\u003eCoercivity of Cu-Fe alloys with different Fe contents (a) M\u003csub\u003es\u003c/sub\u003e, (b) M\u003csub\u003er\u003c/sub\u003e, (c) M\u003csub\u003er\u003c/sub\u003e/M\u003csub\u003es\u003c/sub\u003e and (d) H\u003csub\u003ec\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/7172d9da69b728d065ab62e8.png"},{"id":105904898,"identity":"12bb60d8-97e6-4ef6-a35e-93c7cf3dc3b5","added_by":"auto","created_at":"2026-04-01 10:10:59","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":42146,"visible":true,"origin":"","legend":"\u003cp\u003eSE of Cu-Fe alloys with different Fe contents.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/732ba41a3393491c623a3d74.png"},{"id":105871793,"identity":"16a3ab39-8f3a-4b17-b72b-e2a4bb37e90b","added_by":"auto","created_at":"2026-04-01 04:53:06","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":820206,"visible":true,"origin":"","legend":"\u003cp\u003eThe diagram of EMI shielding mechanisms for Cu-Fe alloys.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/f2e544f4e585e1aa2d0a3de5.png"},{"id":105871795,"identity":"6099487d-1c16-4b38-8b66-5685578c3f21","added_by":"auto","created_at":"2026-04-01 04:53:06","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":42698,"visible":true,"origin":"","legend":"\u003cp\u003eSSE of Cu-Fe alloys with different Fe contents.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/f5a299cbbf861c0bc13585c8.png"},{"id":105906602,"identity":"0d382327-8cb6-4c28-8a61-78e5064a8103","added_by":"auto","created_at":"2026-04-01 10:23:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3335919,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9084786/v1/c2d310ff-3ae7-4b34-906d-5b119b69e155.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Tunable and efficient electromagnetic interference shielding properties of Cu-Fe alloy prepared by powder metallurgy","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eWith the rapid development of electronic information technology, excessive electromagnetic (EM) radiation produced by electronic devices and information transmission not only disrupts the normal operation of electronic equipment but also endangers human health \u003csup\u003e[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. Therefore, EM radiation pollution has become the fifth most prevalent pollution after air, water, noise, and solid waste \u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. To reduce the intensity of EM radiation to a safe range, EM shielding materials is an effective strategy to solve the problems caused by EM radiation pollution. Currently, many kinds of EM shielding materials have been studied, including metal, carbon, ceramic polymer, and composite materials \u003csup\u003e[\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. Among them, metal and carbon are the main functional materials that provide shielding ability.\u003c/p\u003e \u003cp\u003eMetal EM shielding materials such as Magnesium (Mg), Aluminum (Al), Copper (Cu) and their alloys with excellent electrical conductivity, suitable mechanical, low-cost, and high surface gloss have potential applications in the 3C products, automobiles, and aerospace fields. It\u0026rsquo;s worth noting that Copper alloys, also known as a traditional electronic packaging material, not only possesses good heat dispersion due to their high thermal conductivity, but also presents the favorable EM shielding properties caused by the high electrical conductivity, indicating their potential applications in 5G integrated high-power chips of 3C products \u003csup\u003e[\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e. Furthermore, the copper component contributes to enhance EMI shielding properties at high frequencies, while the addition of magnetic iron for Cu-based alloys improves the EMI shielding at low frequencies.\u003c/p\u003e \u003cp\u003eOver the past decade, Cu-Fe alloys have been widely studied as EMI shielding materials to obtain the desired combination of the mechanical properties and electrical conductivity for the applications in the integrated circuits and electronic industries \u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. Wu et al. found that Cu-Fe alloys with higher Fe content exhibited higher strength and lower electrical conductivity, which are ascribed to the strengthening and electron scattering effects owing to the generation of dendritic structure \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. Wang et al. demonstrated through experiments that the electrical conductivity and tensile strength of Cu-10Fe alloys prepared by multi-stage thermomechanical treatment process could reach 58% IACS and 608 MPa, respectively \u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. Compared with Cu metal, the less atomic scattering in Cu-10Fe alloys occurs due to the fewer vacancy and dislocation defects within the Cu matrix after aging, and thus the increased conductivity can be attributed to the precipitation of Fe atoms. In addition, the conductivity and mechanical properties can also be controlled by heat treatment under different temperatures. Qu et al. investigated the electrical conductivity of Cu-15Fe alloys annealed at different temperatures. The results revealed that an increase of filament spacing and reduction of interface area results in the increase of conductivity with increasing temperature below 500 \u003csup\u003eo\u003c/sup\u003eC, while the conductivity values represent a decreasing trend above 500 \u003csup\u003eo\u003c/sup\u003eC due to the rapidly increase of Fe solubility in Cu-matrix \u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e. In the aspect of EMI shielding properties, Pang et al. prepared Cu-10Fe and Cu-10Fe-0.4Si alloys by melting and casting method and investigated the effect of Si on the properties of Cu-10Fe alloy \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAs is well-known, Cu-Fe alloys filled with higher Fe content are beneficial for improving the EMI shielding properties in the low frequency regions, which are commonly emitted from 3C products in our dairy life. However, The traditional preparation methods, including in-situ production and rapid solidification, are difficult to produce Cu-Fe alloys with high Fe content due to the disadvantages of Cu(Fe)-rich phases and the segregation of Fe phase \u003csup\u003e[\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. By comparation, the alloys prepared by powder metallurgy possesses the double advantages of uniform organization and fine grain size, as well as the easy and effective regulations of component content to eliminate composition segregation \u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e. Reports on the microstructure and EMI shielding properties of Cu-Fe alloys with high Fe content fabricated by powder metallurgy process are very limited. In this study, Cu-Fe alloys with 20\u0026ndash;50 wt.% Fe content were prepared by hot-pressed sintering followed by hot rolling. The microstructure, physical properties and EMI shielding properties were systematically investigated, and the possible EMI shielding mechanisms affected by electrical conductivity and magnetic property related to Fe content were also discussed. The Cu-Fe alloys fabricated here could be qualified as an idea candidate for EMI shielding applications in the fields of electronics and communication.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Sample preparation\u003c/h2\u003e \u003cp\u003eElectrolytic copper powder with an average particle size of ~\u0026thinsp;50 \u0026micro;m and high-purity iron powder with ~\u0026thinsp;5 \u0026micro;m average diameter were used as raw materials. In the whole process, 20, 30, 40 and 50 wt.% iron powders were uniformly mixed with copper powders in a planetary ball mill for 4 h. The ratio of ball to powders was 6:1 and the rotation speed was 250 r/min in the ball milling process. Subsequently, the mixed powders after ball milling were vacuum hot-pressing sintered at 980\u0026deg;C for 2 h under a load of 45 MPa in a graphite mold with 40 mm diameter and 80 mm height. Finally, the sintered samples were hot rolled at 800\u0026deg;C followed by a polishing with sandpaper to remove the oxide layer, and the Cu-Fe alloy sheets with thickness of 0.24 mm were obtained. The whole preparation process is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Characterization\u003c/h2\u003e \u003cp\u003eThe density of the samples was tested via the Archimedean method \u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. The phase composition was measured by X-ray diffraction (XRD, Philips X 'pert MPD) in the 2θ range of 20\u003csup\u003eo\u003c/sup\u003e-100\u003csup\u003eo\u003c/sup\u003e with the use of Cu-Kα radiation. Scanning electron microscopy (SEM, Hitachi S-4800) was used to observe the microstructure of the samples, and the element distribution was performed by X-ray energy dispersive spectroscopy (EDS). The electrical conductivity of the samples with a dimension of 35 mm \u0026times; 3 mm \u0026times; 1 mm was tested with four-probe method at room temperature. The magnetic properties were determined by a vibrating sample magnetometer (Lakeshore-7400s), and the weight of the samples was controlled to be about 10 mg. For EMI shielding testing, the samples were processed into a thin metal disc with 133 mm diameter and 0.24 mm thickness, and the EMI shielding effectiveness were conducted by a DR-S03 coaxial shielding effectiveness testing device in the frequency range of 30 MHz\u0026thinsp;\u0026minus;\u0026thinsp;1.5 GHz. The testing device is mainly composed of vector network analyzer, transmission line and coaxial flange components, and the schematic diagram is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Phase composition\u003c/h2\u003e \u003cp\u003eCu-Fe alloys are usually composed of body-centered cubic (Bcc) α-Fe and Fcc-Cu phases \u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the XRD patterns of the prepared Cu-Fe alloys with different Fe contents. As can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the constituent phases of the alloys are Cu and α-Fe, indicating the existence of mixtures. The Cu phase presents obvious diffraction peaks at 43.3\u0026deg;, 50.4\u0026deg;, 74.1\u0026deg; and 89.9\u0026deg;, corresponding to crystallographic indices of (111), (200), (220) and (311), respectively \u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e. The diffraction peak of α-Fe is strongest at 44.7\u0026deg;, and it corresponds to the (110) crystal plane index. With the increase of Fe content, the intensity of the Cu diffraction peaks gradually decreases, while that of the Fe diffraction peak at 44.7\u0026deg; presents an opposite trend. In addition, the shift of diffraction peaks for Cu and Fe phases has not been observed in the XRD patterns, demonstrating that the Cu-Fe alloys prepared here were not oxidized during the process of hot-pressed sintering.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Microstructure and EDS analysis\u003c/h2\u003e \u003cp\u003eThe microstructure of Cu-Fe alloys with 20, 30, 40 and 50 wt.% Fe content is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a-d). According to the backscattered electron (BSE) images shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a-d), the Cu-Fe alloys consist of primary α-Fe phases with dark region random distributed in the brightly colored Cu matrix, and Fe and Cu basically exist in the form of mixtures. The Fe phases with the size ranging from 5 to 40\u0026micro;m are elongated and irregular after the rolling process. Meanwhile, some micro-scaled pores, a typical characteristic of the samples fabricated by hot-pressed sintering, can be observed, appearing as black dots. In addition, with the increase of iron content, the distance between the iron phases evidently decreases, resulting in the formation of iron clusters for the Cu-Fe alloys with higher Fe content. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(e) shows the microstructure and element distribution of hot-pressing sintered Cu-20Fe alloys followed by hot-rolling, which indicates the random distribution of Fe fillers and the existence of numerous Cu/Fe interfaces. It is worth noting that the Cu/Fe interfaces are beneficial for multiple scattering of incident electromagnetic waves, which effectively improve the EMI shielding properties.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Electrical conductivity and magnetic properties\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the electrical conductivity plots for Cu-Fe alloys with different Fe contents. It is clearly observed that the electrical conductivity decreases significantly with the increase of Fe content. Based on the above discussions in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the Fe phase in Cu-Fe alloys exists in the form of magnetic α-Fe (Bcc), which effective scattering the conduction electrons in the electric field \u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e. Furthermore, as increasing the Fe content, the orientation of large-angle grain boundary gradually increases, contributing to the higher resistivity \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. In addition, the internal stress exists at the grain boundaries due to the much harder extrusion forming of Fe relative to Cu in the rolling process. Hence, more lattice strain is generated as Fe content increases, which also results in the decrease of electrical conductivity \u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e. Therefore, the possibility scattering of the conduction electrons, the large-angle grain boundaries, and the lattice strain at the Cu/Fe interfaces leads to a significant decrease in the electrical conductivity of the investigated Cu-Fe alloys as increasing the Fe content.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe hysteresis loops of Cu-Fe alloys with different Fe contents are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The results show that the saturation magnetic induction intensity increases with the increase of Fe content. After hot rolling, the Cu-Fe alloys is still composed of Fcc-Cu and magnetic Bcc-Fe. Each Fe atom has a complete magnetic moment, and every two Fe atoms are magnetically paired during the forming process. As increasing Fe content, the numbers of paired magnetic Fe atoms in Cu-Fe alloys increases, and the more clusters are prone to form. Thus, the Cu-50Fe alloy exhibits the highest value of saturation magnetic induction intensity due to its highest Fe content for our prepared Cu-Fe alloys in this study.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e exhibits the magnetic properties of Cu-Fe alloys with varying Fe contents. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(a-b) reveals that the saturation magnetic induction (M\u003csub\u003es\u003c/sub\u003e) and remanent magnetization (M\u003csub\u003er\u003c/sub\u003e) of the Cu-Fe alloys increase with the increase of Fe content. It is worth mentioning that the M\u003csub\u003er\u003c/sub\u003e values increase greatly for the Cu-Fe alloys with 30 wt.% to 40 wt.% Fe contents, which can be attributed to the transformation of soft magnetic and hard magnetic properties of the alloys. From Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(c-d), it can be observed that the magnetic remanence ratio (M\u003csub\u003er\u003c/sub\u003e/M\u003csub\u003es\u003c/sub\u003e) and coercivity (H\u003csub\u003ec\u003c/sub\u003e) of the alloys increases more significantly as the Fe content increases from 30wt.% to 50wt.%. As everyone knows, the defects (such as dislocations and grain boundaries) and impurities suppress the electron spin and thus increase the coercivity \u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e. With increasing the Fe content, the large angle grain boundaries orientation, and the degree of strain in Cu atoms increase. As a results, an increase in electron spin contributes to the increase of the coercivity for the studied Cu-Fe alloys.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Electromagnetic interference shielding effectiveness\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e exhibits the EMI shielding effectiveness (SE) curves of Cu-Fe alloys with different Fe content. It can be clearly observed that the SE values gradually decrease with the increase of frequency. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, the SE values of Cu-Fe alloys with 20wt.% to 50 wt.% Fe contents are stable at above 100 dB in 30\u0026thinsp;~\u0026thinsp;400 MHz, and their high permeability and low reluctance characteristics play dominant roles in the favorable EMI shielding properties for the low-frequency range. It can be also observed that the SE values of Cu-Fe alloys exhibit a slightly decreasing trend with increasing the Fe content. As is known to all, the EMI shielding properties of the alloys are determined by the conductivity and magnetic properties. According to the discussion in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, the conductivity values are much higher for the alloys with lower Fe content, which contributes to the enhanced SE values. However, owing to the dominant role of the magnetic properties on the EMI shielding effectiveness in the low frequency as shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, no significant increase in the SE values can be observed in the low frequency range.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFurthermore, the SE values present a significant downward trend as increasing the frequency from 400MHz to 1500MHz, especially for the Cu-30Fe, Cu-40Fe, and Cu-50Fe alloys. In the high-frequency range, the obvious decrease of SE values can be mainly attributed to the decrease of conductivity \u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e, resulting in the decrease of the induced current. Significantly, the decrease of the induced current would lead to the decrease in the offset magnetic field, which furtherly reduces the magnetic loss of the EMI shielding material. Meanwhile, conductive carriers are generated on the surface of the alloys in a changing electromagnetic field, and the carriers will shift from disorder to order along with directional drift. Most notably, the directional drift of carrier can form conduction current, and the electromagnetic energy is dissipated in the form of heat, known as conductance loss. Therefore, for the investigated Cu-Fe alloys, the EMI shielding properties can be effective regulated by the electrical conductivity and magnetic properties, and the EMI shielding mechanisms of Cu-Fe alloys against incident electromagnetic wave are composed of reflection, absorption loss and conductance loss \u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e, which is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn addition, it can be found that the Cu-40Fe alloy present a relatively much higher EMI shielding effeteness compared with the Cu-30Fe and Cu-40Fe alloys. As everyone knows, EMI shielding properties are significantly affected by the thickness of the testing samples, and Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the parameters of the samples. Based on the discussion of Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(a) and Table.1, the higher EMI shielding effeteness of Cu-40Fe alloy can be ascribed to the fact that its thickness is much higher than that of Cu-30Fe and Cu-50Fe samples. Based on the previous reports, the average SE value of Cu-10Fe with 1.0mm thickness is 104.6 dB in 30 MHz\u0026thinsp;~\u0026thinsp;1.5 GHz \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. By comparation, the average SE value of Cu-20Fe alloy with 0.24mm thickness stabilizes at 109.7dB over the entire frequency range, exhibiting the highest EMI shielding properties for our investigated Cu-Fe alloys.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eParameters of the testing samples\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCu-Fe alloys\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDensity (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRelative density (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eThickness(mm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCu-20Fe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCu-30Fe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.4676\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e98.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCu-40Fe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.1739\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCu-50Fe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.3483\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e99.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eTo eliminate the effect of thickness and density on the EMI shielding effeteness, the specific shielding effectiveness (SSE) can be used to express the EMI shielding properties of the alloys, and the expression formula is presented as follows:\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003cdiv id=\"Equ1\" class=\"Equation\"\u003e \u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:SSE=\\frac{SE}{\\rho\\:\\times\\:d}$$\u003c/div\u003e \u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ewhere SE (dB) represents the electromagnetic shielding effectiveness, ρ (g/cm\u003csup\u003e3\u003c/sup\u003e) is the density, d (cm) is the thickness, and the units of SSE are dB.cm\u003csup\u003e2\u003c/sup\u003e.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e presents the SSE of Cu-Fe alloys with different Fe content. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, the SSE values of Cu-Fe alloys with 30, 40, and 50wt.% Fe contents exhibit a significant downward trend, which is mainly attributed to the decrease of electrical conductivity. By comparation, the H\u003csub\u003ec\u003c/sub\u003e values of Cu-40Fe and Cu-50Fe alloys tend to be stable, and thus no significant difference in SSE values can be observed. In conclusion, for the Cu-Fe alloys with 10\u0026ndash;50 wt.% Fe contents based on this study and previous report, Cu-20Fe alloy in this study presents the highest EMI shielding properties, exhibiting the more favorable electromagnetic shielding performance, and its SSE value is stable at 542 dB.cm\u003csup\u003e2\u003c/sup\u003e.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in 30 MHz\u0026thinsp;~\u0026thinsp;1.5 GHz.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn this study, Cu-Fe alloys with different Fe contents were prepared by hot-pressed sintering followed by hot rolling. Microstructure, electrical conductivity, and magnetic properties were analyzed, and the electromagnetic interference (EMI) shielding properties were investigated in the frequency range of 30 MHz\u0026thinsp;~\u0026thinsp;1.5 GHz. The results show that the Cu-Fe alloys are composed of Cu phase and magnetic α-Fe phase, existing in the form of mixtures. As increasing Fe content, the electrical conductivity decreases significantly, while the saturation magnetic induction intensity and the coercivity present an increasing trend. In addition, the EMI shielding properties of Cu-Fe alloy decreases gradually with the increase of Fe content in the low-frequency range, and the SE values present a significant downward trend as increasing the frequency in the high-frequency region. Owing to the suitable conductivity and magnetic properties, the average SE value of Cu-20Fe alloy with 0.24mm thickness stabilizes at 109.7dB over the entire frequency range, exhibiting the favorable EMI shielding properties for our investigated Cu-Fe alloys. The excellent EMI shielding properties were attributed to the reflection, absorption loss and conductance loss, and the Cu-Fe alloys fabricated here could be qualified as an idea candidate for EMI shielding applications in the fields of electronics and communication.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eCompeting interest\u003c/h2\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003ch2\u003eEthical approval\u003c/h2\u003e\n\u003cp\u003eThe authors declare that there are no potential conflicts of interest and that no part of this research involves human participants and/or animals.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eLiang Zhou, MUHAIMINUL ISLAM SHAKIL and Yanrong Feng wrote the main manuscript text, while Yaping Wang, Zhaorui Zhang and Fudong Nan prepared figures 1-10. All authors reviewed the manuscript.\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eThis work was financially supported by Natural Science Foundation of Shaanxi Province (No. 2021JLM-41), Key Research and Development Program in Shaanxi Province of China (No. 2025CY-YBXM-128), and the Fundamental Research Funds for the Central Universities from Chang\u0026apos;an University (No. 300102313201).\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eAll authors hereby declare that the data involved in this research are true. Moreover, such data will be provided as required.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWu N, Hu Q, Wei R\u003cem\u003e et al.\u003c/em\u003e Review on the electromagnetic interference shielding properties of carbon based materials and their novel composites: Recent progress, challenges and prospects. 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Composites Science and Technology 2019; 172:66-73.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Cu-Fe alloys, Conductivity, Magnetic property, Electromagnetic interference shielding, Hot-pressing, Hot-rolling","lastPublishedDoi":"10.21203/rs.3.rs-9084786/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9084786/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMicrostructure, electrical conductivity, magnetic properties, and electromagnetic interference (EMI) shielding properties of hot-pressed and hot-rolled Cu-Fe alloys were investigated in this paper. The results show that the Cu-Fe alloys are Cu and magnetic α-Fe mixtures. As increasing Fe content, the electrical conductivity decreases significantly, while the saturation magnetic induction intensity and the coercivity present an evident increasing trend. The EMI shielding effectiveness (SE) of Cu-Fe alloy decreases gradually with increasing Fe content in low frequency, and the SE values present a significant downward trend as increasing the frequency in high frequency. Owing to the suitable conductivity and magnetic properties, the average SE value of Cu-20Fe alloy with 0.24mm thickness stabilizes at 109.7dB over the entire frequency range, indicating the tunable and efficient EMI shielding properties. The Cu-Fe alloys fabricated here could be qualified as an idea candidate for EMI shielding applications in the electronic and communication field.\u003c/p\u003e","manuscriptTitle":"Tunable and efficient electromagnetic interference shielding properties of Cu-Fe alloy prepared by powder metallurgy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-01 04:53:01","doi":"10.21203/rs.3.rs-9084786/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e1adcc43-f58a-446c-9256-218e2c60fea9","owner":[],"postedDate":"April 1st, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-27T00:23:48+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-01 04:53:01","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9084786","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9084786","identity":"rs-9084786","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}