Pub Date : 2026-01-15DOI: 10.1016/j.scriptamat.2026.117180
Hong Lian , Qi Miao , Xinwei Shi , Yilin Wang , Kaiyue Zhao , Juan Guo , Erjun Liang , Qilong Gao
Zero thermal expansion (ZTE) materials hold significant application potential in precision industrial equipment. Based on the design concept of average atomic volume, this study successfully constructed the KxMgxIn2-xMo3O12:0.15Yb3+/0.03Er3+(x = 0.4∼1.0) material series through innovative modifications to the NASICON-type structure. This was achieved by replacing the PO4 tetrahedra (1.856Å3) in the conventional NZP framework with larger MoO4 tetrahedra (3.099Å3) and introducing a K+-Mg2+/In3+ combination to achieve charge balance and lattice expansion. This is attributed to the reduced K⁺ content enhancing the lateral vibrational ability of oxygen atoms, thereby counteracting thermal expansion; simultaneously, as the volumetric thermal expansion coefficient approaches zero, the thermally enhanced upconversion luminescence effect gradually intensifies. This study achieved controllable regulation of thermal expansion and obtained ZTE materials, providing new insight for elucidating the intrinsic relationship between thermal expansion and luminescence thermal enhancement.
{"title":"Realizing zero thermal expansion in NaSICON structure framework materials via controlling guest ions","authors":"Hong Lian , Qi Miao , Xinwei Shi , Yilin Wang , Kaiyue Zhao , Juan Guo , Erjun Liang , Qilong Gao","doi":"10.1016/j.scriptamat.2026.117180","DOIUrl":"10.1016/j.scriptamat.2026.117180","url":null,"abstract":"<div><div>Zero thermal expansion (ZTE) materials hold significant application potential in precision industrial equipment. Based on the design concept of average atomic volume, this study successfully constructed the K<em><sub>x</sub></em>Mg<em><sub>x</sub></em>In<sub>2-</sub><em><sub>x</sub></em>Mo<sub>3</sub>O<sub>12</sub>:0.15Yb<sup>3+</sup>/0.03Er<sup>3+</sup>(<em>x</em> = 0.4∼1.0) material series through innovative modifications to the NASICON-type structure. This was achieved by replacing the PO<sub>4</sub> tetrahedra (1.856Å<sup>3</sup>) in the conventional NZP framework with larger MoO<sub>4</sub> tetrahedra (3.099Å<sup>3</sup>) and introducing a K<sup>+</sup>-Mg<sup>2+</sup>/In<sup>3+</sup> combination to achieve charge balance and lattice expansion. This is attributed to the reduced K⁺ content enhancing the lateral vibrational ability of oxygen atoms, thereby counteracting thermal expansion; simultaneously, as the volumetric thermal expansion coefficient approaches zero, the thermally enhanced upconversion luminescence effect gradually intensifies. This study achieved controllable regulation of thermal expansion and obtained ZTE materials, providing new insight for elucidating the intrinsic relationship between thermal expansion and luminescence thermal enhancement.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117180"},"PeriodicalIF":5.6,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yield strength anomaly (YSA), characterized by increased strength at elevated temperatures, is crucial for the performance of superalloys in high-temperature applications. However, the observation of YSA is seldomly reported in high entropy alloys (HEAs). This work unveils the origin of YSA in a γ′-strengthened HEA, Co₃₇.₆Ni₃₅.₄Al₉.₉Cr₅.₉Mo₄.₉Ti₃.₅Ta₂.₈, containing >75% γ′ phase. The alloy exhibits a peak yield strength of 772 ± 11 MPa at 770 °C. Scanning and transmission electron microscopy (S/TEM) reveal the formation of superlattice intrinsic stacking faults (SISFs) on non-coplanar {111} planes, whose interactions result in a high density of Lomer-Cottrell (L-C) locks, thereby contributing to the strength anomaly. The deformation substructure evolution below and above the anomaly peak temperature (670 °C and 870 °C) revealed γ′ precipitates are sheared by SISF- and anti-phase boundary-coupled super-partial dislocations. The persistence of L-C locks at 870 °C leads to higher strength than 670 °C, underscoring their role in strengthening in the low stacking fault energy system at elevated temperatures.
{"title":"On the origin of yield strength anomaly in a γ/γ′ strengthened high entropy alloy","authors":"Abhijit Chhotray , Roopchand Tandon , Sanjay Kashyap , Prafull Pandey","doi":"10.1016/j.scriptamat.2025.117152","DOIUrl":"10.1016/j.scriptamat.2025.117152","url":null,"abstract":"<div><div>Yield strength anomaly (YSA), characterized by increased strength at elevated temperatures, is crucial for the performance of superalloys in high-temperature applications. However, the observation of YSA is seldomly reported in high entropy alloys (HEAs). This work unveils the origin of YSA in a γ′-strengthened HEA, Co₃₇.₆Ni₃₅.₄Al₉.₉Cr₅.₉Mo₄.₉Ti₃.₅Ta₂.₈, containing >75% γ′ phase. The alloy exhibits a peak yield strength of 772 ± 11 MPa at 770 °C. Scanning and transmission electron microscopy (S/TEM) reveal the formation of superlattice intrinsic stacking faults (SISFs) on non-coplanar {111} planes, whose interactions result in a high density of Lomer-Cottrell (L-C) locks, thereby contributing to the strength anomaly. The deformation substructure evolution below and above the anomaly peak temperature (670 °C and 870 °C) revealed γ′ precipitates are sheared by SISF- and anti-phase boundary-coupled super-partial dislocations. The persistence of L-C locks at 870 °C leads to higher strength than 670 °C, underscoring their role in strengthening in the low stacking fault energy system at elevated temperatures.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117152"},"PeriodicalIF":5.6,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
TiVZrNbHf bcc high entropy alloy shows promising hydrogen storage capacity, but unfavourable thermodynamics of the hydride phases i.e., too stable hydrides requiring high temperatures for recovering the stored hydrogen. Mo addition in this composition ((TiVZrNbHf)100-xMoxx = 5, 10 and 16.666) preserves the bcc lattice, decreases the lattice parameter and improves the hydrogen absorption kinetics at room temperature. Moreover, it effectively destabilizes both the bct intermediate and full fcc hydride phases without significant affecting the maximum storage capacity (∼ 2.1 wt. %). The temperatures of successive phase transitions (fcc → bct → bcc) during deuterium desorption strongly reduce with increasing Mo content, as demonstrated by in situ neutron powder diffraction. Several entangled factors can be invoked to explain this thermal destabilization along with electronic structure, steric and electronegativity effects. Therefore, Mo can be proposed as one of the most effective boosting elements to be added in HEAs for hydrogen storage.
TiVZrNbHf bcc高熵合金表现出良好的储氢能力，但氢化物相热力学不利，即氢化物太稳定，需要高温才能回收储存的氢。在该组合物（(TiVZrNbHf)100-xMox x = 5,10和16.666）中添加Mo保留了bcc晶格，降低了晶格参数，改善了室温下的吸氢动力学。此外，它有效地破坏了bct中间和全fcc氢化物相的稳定，而不会显著影响最大存储容量（~ 2.1 wt. %）。原位中子粉末衍射结果表明，随着Mo含量的增加，氘脱附过程中连续相变（fcc→bct→bcc）的温度明显降低。可以用几个纠缠的因素来解释这种热不稳定性以及电子结构、空间和电负性效应。因此，Mo可以作为HEAs储氢中最有效的助推元素之一。
{"title":"Effective destabilization of both mono- and dihydride phases in TiVZrNbHf by Mo addition","authors":"Andrei Agafonov , Faye Greaves , Loïc Perrière , Vivian Nassif , Claudia Zlotea","doi":"10.1016/j.scriptamat.2025.117161","DOIUrl":"10.1016/j.scriptamat.2025.117161","url":null,"abstract":"<div><div>TiVZrNbHf <em>bcc</em> high entropy alloy shows promising hydrogen storage capacity, but unfavourable thermodynamics of the hydride phases <em>i.e.,</em> too stable hydrides requiring high temperatures for recovering the stored hydrogen. Mo addition in this composition ((TiVZrNbHf)<sub>100-<em>x</em></sub>Mo<sub><em>x</em></sub> <em>x</em> = 5, 10 and 16.666) preserves the <em>bcc</em> lattice, decreases the lattice parameter and improves the hydrogen absorption kinetics at room temperature. Moreover, it effectively destabilizes both the <em>bct</em> intermediate and full <em>fcc</em> hydride phases without significant affecting the maximum storage capacity (∼ 2.1 wt. %). The temperatures of successive phase transitions (<em>fcc</em> → <em>bct</em> → <em>bcc</em>) during deuterium desorption strongly reduce with increasing Mo content, as demonstrated by <em>in situ</em> neutron powder diffraction. Several entangled factors can be invoked to explain this thermal destabilization along with electronic structure, steric and electronegativity effects. Therefore, Mo can be proposed as one of the most effective boosting elements to be added in HEAs for hydrogen storage.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117161"},"PeriodicalIF":5.6,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1016/j.scriptamat.2026.117169
Yingji Sang , Liangyu Li , Jie Li , Qing Chen
Nanoporous metal, fabricated via the selective dissolution of an alloy (i.e., dealloying), can be filled with another metal via electrodeposition to create unique, functional structures unattainable via just dealloying. In this work, by controlling the charge of Ni deposition, we finetune the porosity and the pore width of nanoporous copper. At a sufficiently low rate, the deposition proceeds uniformly under interface control, until the porosity approaches a percolation threshold, which also governs the smallest attainable pore width. Via microscopic characterizations, we determine that we can tune down the porosity from 57.5 % to 15.8 % and the pore width from 89 nm to 34 nm. A tuned structure that retains the structural bi-continuity rejects 80 % KCl from a 1 mM solution, a function not available in the pristine structure but enabled by the narrowed pores.
{"title":"Structural tuning of nanoporous metal via electrodeposition","authors":"Yingji Sang , Liangyu Li , Jie Li , Qing Chen","doi":"10.1016/j.scriptamat.2026.117169","DOIUrl":"10.1016/j.scriptamat.2026.117169","url":null,"abstract":"<div><div>Nanoporous metal, fabricated via the selective dissolution of an alloy (i.e., dealloying), can be filled with another metal via electrodeposition to create unique, functional structures unattainable via just dealloying. In this work, by controlling the charge of Ni deposition, we finetune the porosity and the pore width of nanoporous copper. At a sufficiently low rate, the deposition proceeds uniformly under interface control, until the porosity approaches a percolation threshold, which also governs the smallest attainable pore width. Via microscopic characterizations, we determine that we can tune down the porosity from 57.5 % to 15.8 % and the pore width from 89 nm to 34 nm. A tuned structure that retains the structural bi-continuity rejects 80 % KCl from a 1 mM solution, a function not available in the pristine structure but enabled by the narrowed pores.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117169"},"PeriodicalIF":5.6,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-10DOI: 10.1016/j.scriptamat.2025.117164
Abdullatif Durgun , Imants Dirba , Konrad Opelt , Chi-Chia Lin , Jürgen Gassmann , Oliver Gutfleisch
To enhance coercivity in high-performance Nd-Fe-B magnets, resource critical heavy rare earth elements Dy and Tb are used in the grain boundary diffusion process (GBDP). However, GBDP is limited to thin magnets, typically around 4 mm which restricts their applications. Here, we report a novel processing route by combining the GBDP process with a magnet stacking architecture using a < 10 μm thin low-melting multi-element Tb₁₀Pr₆₀Al₁₀Cu₁₀Ga₁₀ alloy which has now a dual function: it acts as a binder between the magnet segments and is at the same time an efficient source for core-shell formation on the individual crystallite level. This not only enables production of magnets with any thickness without losing performance, but also paves the way for resource efficiency using cheap and abundant light rare earth Cerium in hybrid magnets by strategically stacking different grades with tailored chemical compositions resulting in a unique macroscopic magnetic hardening.
{"title":"Combining grain boundary diffusion and segmentation: A novel production route for resource-efficient Nd–Fe–B magnets","authors":"Abdullatif Durgun , Imants Dirba , Konrad Opelt , Chi-Chia Lin , Jürgen Gassmann , Oliver Gutfleisch","doi":"10.1016/j.scriptamat.2025.117164","DOIUrl":"10.1016/j.scriptamat.2025.117164","url":null,"abstract":"<div><div>To enhance coercivity in high-performance Nd-Fe-B magnets, resource critical heavy rare earth elements Dy and Tb are used in the grain boundary diffusion process (GBDP). However, GBDP is limited to thin magnets, typically around 4 mm which restricts their applications. Here, we report a novel processing route by combining the GBDP process with a magnet stacking architecture using <em>a</em> < 10 μm thin low-melting multi-element Tb₁₀Pr₆₀Al₁₀Cu₁₀Ga₁₀ alloy which has now a dual function: it acts as a binder between the magnet segments and is at the same time an efficient source for core-shell formation on the individual crystallite level. This not only enables production of magnets with any thickness without losing performance, but also paves the way for resource efficiency using cheap and abundant light rare earth Cerium in hybrid magnets by strategically stacking different grades with tailored chemical compositions resulting in a unique macroscopic magnetic hardening.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117164"},"PeriodicalIF":5.6,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-10DOI: 10.1016/j.scriptamat.2026.117168
Lei Jiang , Xinbiao Zhang , Juan Du , Zheng Shi , Zhihao Zhang , Jianxin Xie
Achieving a synergistic enhancement of the inherently conflicting tensile strength and stress corrosion resistance in 7000-series aluminum alloys has long been a major challenge. In this study, we demonstrate that adopting an appropriate natural aging pretreatment after solution treatment enables the alloy, in its peak-aged condition, to develop intragranular precipitates with higher number density and more uniform size distribution, as well as grain boundary precipitates with significantly reduced size and an increased Mg/Zn ratio. These microstructural modifications result in the simultaneous improvement of both strength and stress corrosion resistance. Taking the newly designed Al-10.2Zn-2.32Mg-1.35Cu-0.1Cr-0.1Zr alloy as an example, after a 10-day natural aging pretreatment, the stress corrosion sensitivity factor of the alloy in the peak-aged condition is significantly reduced from 25.0 % ± 0.8 % to 10.7 % ± 0.9 %, while maintaining a certain enhancement in tensile strength. This study provides a new pathway for balancing strength and stress corrosion resistance in ultra-high-strength aluminum alloys.
{"title":"Significant enhancement of stress corrosion resistance without strength degradation in Al-Zn-Mg-Cu alloys via natural aging pretreatment","authors":"Lei Jiang , Xinbiao Zhang , Juan Du , Zheng Shi , Zhihao Zhang , Jianxin Xie","doi":"10.1016/j.scriptamat.2026.117168","DOIUrl":"10.1016/j.scriptamat.2026.117168","url":null,"abstract":"<div><div>Achieving a synergistic enhancement of the inherently conflicting tensile strength and stress corrosion resistance in 7000-series aluminum alloys has long been a major challenge. In this study, we demonstrate that adopting an appropriate natural aging pretreatment after solution treatment enables the alloy, in its peak-aged condition, to develop intragranular precipitates with higher number density and more uniform size distribution, as well as grain boundary precipitates with significantly reduced size and an increased Mg/Zn ratio. These microstructural modifications result in the simultaneous improvement of both strength and stress corrosion resistance. Taking the newly designed Al-10.2Zn-2.32Mg-1.35Cu-0.1Cr-0.1Zr alloy as an example, after a 10-day natural aging pretreatment, the stress corrosion sensitivity factor of the alloy in the peak-aged condition is significantly reduced from 25.0 % ± 0.8 % to 10.7 % ± 0.9 %, while maintaining a certain enhancement in tensile strength. This study provides a new pathway for balancing strength and stress corrosion resistance in ultra-high-strength aluminum alloys.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117168"},"PeriodicalIF":5.6,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.scriptamat.2025.117160
M.J.K. Lodhi , Yuxin Hu , Ching-Heng Shiau , Brian S. Newell , Benjamin W. Spencer , Peter Hosemann , Fei Teng
Electrodeposited nickel coatings are characterized by high densities of crystalline defects including dislocations, growth twins, and hydrogen bubbles/voids, arising from the non-equilibrium nature of deposition. While these metastable features influence as-deposited properties, their evolution under low temperature annealing remains unexplored. Here we demonstrate that low temperature annealing (200 °C) induces significant microstructural rearrangement without grain growth, enabling defect engineering through thermally assisted dislocation motion and twin boundary migration. Notably, we observe faceted twin boundaries and dislocation organization into extended networks, which have been rarely reported under such annealing conditions. These transformations are attributed to hydrogen-assisted defect mobility, facilitated by the release or redistribution of hydrogen trapped during deposition. These structural transformations correlate with a significant enhancement in mechanical properties, including a twofold increase in yield strength and improved ductility. Our findings highlight the role of trapped hydrogen in mediating low-temperature defect mobility and twin boundary evolution, offering a unique pathway for microstructural tuning of metallic coatings through controlled annealing.
{"title":"Defect engineering in nickel via electrodeposition following low temperature annealing","authors":"M.J.K. Lodhi , Yuxin Hu , Ching-Heng Shiau , Brian S. Newell , Benjamin W. Spencer , Peter Hosemann , Fei Teng","doi":"10.1016/j.scriptamat.2025.117160","DOIUrl":"10.1016/j.scriptamat.2025.117160","url":null,"abstract":"<div><div>Electrodeposited nickel coatings are characterized by high densities of crystalline defects including dislocations, growth twins, and hydrogen bubbles/voids, arising from the non-equilibrium nature of deposition. While these metastable features influence as-deposited properties, their evolution under low temperature annealing remains unexplored. Here we demonstrate that low temperature annealing (200 °C) induces significant microstructural rearrangement without grain growth, enabling defect engineering through thermally assisted dislocation motion and twin boundary migration. Notably, we observe faceted twin boundaries and dislocation organization into extended networks, which have been rarely reported under such annealing conditions. These transformations are attributed to hydrogen-assisted defect mobility, facilitated by the release or redistribution of hydrogen trapped during deposition. These structural transformations correlate with a significant enhancement in mechanical properties, including a twofold increase in yield strength and improved ductility. Our findings highlight the role of trapped hydrogen in mediating low-temperature defect mobility and twin boundary evolution, offering a unique pathway for microstructural tuning of metallic coatings through controlled annealing.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117160"},"PeriodicalIF":5.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.scriptamat.2025.117150
P.D. Unnikrishnan , M. Kamaraj , Christopher C. Berndt , Andrew Siao Ming Ang , Srinivasa Rao Bakshi
Cold-sprayed copper coatings are characterized by a severely deformed, heterogeneous microstructure, resulting in inherent brittleness. This brittleness stems from weak interparticle bonding, micro-pores, high plastic strain and dislocation density along with fine dynamically recrystallized grains at interfaces, which facilitate easy crack propagation. While annealing treatments are known to enhance metallurgical bonding and induce recrystallization, a significant improvement in failure strain remains elusive even after complete recrystallization. The fundamental impact of annealing on this complex, severely deformed microstructure is not yet fully understood. This study presents an in-depth investigation into the microstructural evolution and mechanical properties of cold-sprayed copper across a range of annealing conditions. Hardness, microstructure, and thermal analysis studies show that recrystallization peaks are below 250 °C, with a relatively lower activation energy of 71 kJ.mol-1, indicative of high stored energy. The mechanism of bimodal grain size formation upon annealing is discussed, which is a primary factor limiting ductility.
{"title":"Microstructural and mechanical response of cold-sprayed copper subjected to annealing","authors":"P.D. Unnikrishnan , M. Kamaraj , Christopher C. Berndt , Andrew Siao Ming Ang , Srinivasa Rao Bakshi","doi":"10.1016/j.scriptamat.2025.117150","DOIUrl":"10.1016/j.scriptamat.2025.117150","url":null,"abstract":"<div><div>Cold-sprayed copper coatings are characterized by a severely deformed, heterogeneous microstructure, resulting in inherent brittleness. This brittleness stems from weak interparticle bonding, micro-pores, high plastic strain and dislocation density along with fine dynamically recrystallized grains at interfaces, which facilitate easy crack propagation. While annealing treatments are known to enhance metallurgical bonding and induce recrystallization, a significant improvement in failure strain remains elusive even after complete recrystallization. The fundamental impact of annealing on this complex, severely deformed microstructure is not yet fully understood. This study presents an in-depth investigation into the microstructural evolution and mechanical properties of cold-sprayed copper across a range of annealing conditions. Hardness, microstructure, and thermal analysis studies show that recrystallization peaks are below 250 °C, with a relatively lower activation energy of 71 kJ.mol<sup>-1</sup>, indicative of high stored energy. The mechanism of bimodal grain size formation upon annealing is discussed, which is a primary factor limiting ductility.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117150"},"PeriodicalIF":5.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.scriptamat.2025.117154
C. Li , H.Z. Zhang , X.Y. Li , Z.L. Ma , X.W. Cheng
Electromigration (EM) effects on intermetallic compound evolution remain incompletely understood despite their critical role in solder joint reliability. Through correlated transmission electron microscopy (TEM) and ab initio molecular dynamics (AIMD) simulations of Sn-3.0Ag-0.5Cu solder joints under current stressing, we reveal for the first time that EM imposes crystallographic selection during η-to-η' transformation in Cu6Sn5—suppressing η' variants via electron-wind-aligned atomic migration while accelerating η' growth. Atomic-scale simulations establish that EM redirects this phase transformation via kinetically impeding atomic shuffling, as indicated by the elevated interfacial shear strain. This newly identified current-steered phase transformation represents a paradigm shift in understanding EM-induced damage—demonstrating that electric fields not only accelerate but also crystallographically constrain solid-state transformations in Cu6Sn5 intermetallic. The resulting anisotropic η'-Cu6Sn5 microstructures may concentrate degradation pathways, highlighting critical implications for reliability in high-current-density microelectronics where texture-dominated failure may emerge.
{"title":"Anisotropic phase transformation of Cu6Sn5 driven by electromigration in lead-free solder joints","authors":"C. Li , H.Z. Zhang , X.Y. Li , Z.L. Ma , X.W. Cheng","doi":"10.1016/j.scriptamat.2025.117154","DOIUrl":"10.1016/j.scriptamat.2025.117154","url":null,"abstract":"<div><div>Electromigration (EM) effects on intermetallic compound evolution remain incompletely understood despite their critical role in solder joint reliability. Through correlated transmission electron microscopy (TEM) and ab initio molecular dynamics (AIMD) simulations of Sn-3.0Ag-0.5Cu solder joints under current stressing, we reveal for the first time that EM imposes crystallographic selection during η-to-η' transformation in Cu<sub>6</sub>Sn<sub>5</sub>—suppressing η' variants via electron-wind-aligned atomic migration while accelerating η' growth. Atomic-scale simulations establish that EM redirects this phase transformation via kinetically impeding atomic shuffling, as indicated by the elevated interfacial shear strain. This newly identified current-steered phase transformation represents a paradigm shift in understanding EM-induced damage—demonstrating that electric fields not only accelerate but also crystallographically constrain solid-state transformations in Cu<sub>6</sub>Sn<sub>5</sub> intermetallic. The resulting anisotropic η'-Cu<sub>6</sub>Sn<sub>5</sub> microstructures may concentrate degradation pathways, highlighting critical implications for reliability in high-current-density microelectronics where texture-dominated failure may emerge.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"275 ","pages":"Article 117154"},"PeriodicalIF":5.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-07DOI: 10.1016/j.scriptamat.2025.117162
Bhawna Yadav , Aditya Burla , G. Mohan Muralikrishna , N. Chandrasekaran , K.G. Pradeep , Mayur Vaidya , Gerhard Wilde , Sergiy V. Divinski
Grain boundary diffusion of Co in a high-pressure torsion-processed equiatomic CoFeNi medium-entropy alloy was investigated using radiotracer technique. The results revealed a retarded relaxation of deformation-induced, non-equilibrium state of grain boundaries. With increasing temperature, the formation and subsequent dissolution of the BCC phase at grain boundaries were observed, while atom probe tomography revealed nanoscale phase separation into Ni-rich FCC and FeCo-rich BCC regions. The combined effects of segregation and chemical complexity are proposed to stabilize the deformation-induced non-equilibrium grain boundary state. High-energy/high-diffusivity grain boundaries are found to survive even after high-temperature annealing treatments due to the chemical complexity of the medium-entropy alloy.
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