Acta Materialia最新文献_第4页

Functional recycling of grain boundary diffusion processed Nd-Fe-B sintered magnets 晶界扩散加工钕铁硼烧结磁体的功能再循环

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-08 DOI: 10.1016/j.actamat.2024.120532

Mario Schönfeldt , Jürgen Rossa , Konrad Opelt , Kilian Schäfer , Lukas Schäfer , Fernando Maccari , Matic Jovičević-Klug , Tim M. Schwarz , Chi-Chia Lin , Mahmudul Hasan , Jürgen Gassmann , Dierk Raabe , Oliver Gutfleisch

{"title":"Functional recycling of grain boundary diffusion processed Nd-Fe-B sintered magnets","authors":"Mario Schönfeldt , Jürgen Rossa , Konrad Opelt , Kilian Schäfer , Lukas Schäfer , Fernando Maccari , Matic Jovičević-Klug , Tim M. Schwarz , Chi-Chia Lin , Mahmudul Hasan , Jürgen Gassmann , Dierk Raabe , Oliver Gutfleisch","doi":"10.1016/j.actamat.2024.120532","DOIUrl":"10.1016/j.actamat.2024.120532","url":null,"abstract":"<div><div>Sintered Nd-Fe-B magnets industrially produced employing the grain boundary diffusion process (GBD) were recycled by the so-called functional or short-loop recycling approach, based on hydrogen decrepitation (HD). Microstructural and magnetic differences between the original and the recycled materials were analyzed. The functional recycling of GBD magnets leads to the dissolution of the core (heavy rare earth lean) - shell (heavy rare earth rich) structure through the different heat treatment steps which include hydrogen decrepitation, sintering, and annealing. The recycled magnets show similar rectangular demagnetization curves with squareness of 96 %, and only a slightly decreased remanence of 5 % to 1.31 T, but a larger decrease in coercivity of 21 % to 1703 kA/m. A new GBD step using 1.5 wt.% Tb with a pure Tb-foil as diffusion source leads again to the formation of a core-shell structure with 0.5 µm thick Tb-shells which is similar to the microstructure of the original magnets prior to recycling. The coercivity of the recycled magnets is increased by 35 % from 1315 kA/m to 1780 kA/m at 50 °C and shows similar magnetic values as the original industrial magnets at 150 °C and 200 °C, respectively. The temperature coefficients for the remanence, α, and for the coercivity, β, can also be fully restored and even exceed the original values which leads to an improved temperature stability of the recycled magnets compared to the original magnets.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120532"},"PeriodicalIF":8.3,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142598535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhanced mechanical hardness of mixed-phase BiFeO3 films through quenching 通过淬火提高混合相 BiFeO3 薄膜的机械硬度

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-07 DOI: 10.1016/j.actamat.2024.120539

Xueli Hu , Shuo Yan , Xiaomei Lu , Fengzhen Huang , Shuyu Xiao

引用次数: 0

Densely packed glass structure caused by seven-coordinated Zr in high elastic modulus Al2O3–SiO2–ZrO2 glasses 高弹性模量 Al2O3-SiO2-ZrO2 玻璃中七配位 Zr 造成的致密玻璃结构

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-06 DOI: 10.1016/j.actamat.2024.120549

Atsunobu Masuno , Yuki Mikami , Yutaka Yanaba , Yuji Higo , Shunta Sasaki , Io Sato , Toyonari Yaji , Gustavo A. Rosales-Sosa , Hiroyuki Inoue

{"title":"Densely packed glass structure caused by seven-coordinated Zr in high elastic modulus Al2O3–SiO2–ZrO2 glasses","authors":"Atsunobu Masuno , Yuki Mikami , Yutaka Yanaba , Yuji Higo , Shunta Sasaki , Io Sato , Toyonari Yaji , Gustavo A. Rosales-Sosa , Hiroyuki Inoue","doi":"10.1016/j.actamat.2024.120549","DOIUrl":"10.1016/j.actamat.2024.120549","url":null,"abstract":"<div><div>Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub>–ZrO<sub>2</sub> ternary glasses were fabricated using a levitation technique. The addition of ZrO<sub>2</sub> to the Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> glasses strongly affected their thermal, mechanical, and structural properties. Several compositions were partially vitrified at the laser-melted area without levitation although their melting required temperatures higher than 2000 °C. With increasing ZrO<sub>2</sub> content, the elastic moduli linearly increased, and the 50Al<sub>2</sub>O<sub>3</sub>–20SiO<sub>2</sub>–30ZrO<sub>2</sub> glass exhibited a Young′s modulus of 166 GPa and Vickers hardness <em>H</em><sub>V</sub> of 10.6 GPa. Conversely, crack resistance significantly decreased with the addition of ZrO<sub>2</sub>. Density measurements, Zr <em>L</em><sub>2,3</sub>-edge and <em>K</em>-edge X-ray absorption fine structure analyses, and <sup>27</sup>Al and <sup>29</sup>Si magic-angle spinning nuclear magnetic resonance spectroscopy were performed to investigate the local structure around Zr, Al, and Si in the glasses. Zr formed distorted ZrO<sub>7</sub> as in monoclinic ZrO<sub>2</sub>, which has been rarely found in conventional oxide glasses. The highly oxygen-coordinated Al atoms such as AlO<sub>5</sub> and AlO<sub>6</sub>, were the main components in the glasses rather than AlO<sub>4</sub>. The majority of Si atoms form SiO<sub>4</sub> with four bridging oxygen (Q<sup>4</sup>). Among the four bridging oxygens, the number of oxygens connected to Al or Zr clearly increased with decreasing SiO<sub>2</sub> content. The high packing density of the ternary glasses that resulted in high elastic moduli originated from the highly oxygen-coordinated Zr and Al and their close bonding with SiO<sub>4</sub> without generating nonbridging oxygens.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120549"},"PeriodicalIF":8.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142588369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Achieving low thermal conductivity and high quality factor in sextuple-doped TiS2 实现六重掺杂 TiS2 的低导热性和高品质因数

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-06 DOI: 10.1016/j.actamat.2024.120548

Jinxue Ding , Wei Li , Moritz Thiem , Konstantin P. Skokov , Nina Kintop , Anke Weidenkaff , Wenjie Xie

{"title":"Achieving low thermal conductivity and high quality factor in sextuple-doped TiS2","authors":"Jinxue Ding , Wei Li , Moritz Thiem , Konstantin P. Skokov , Nina Kintop , Anke Weidenkaff , Wenjie Xie","doi":"10.1016/j.actamat.2024.120548","DOIUrl":"10.1016/j.actamat.2024.120548","url":null,"abstract":"<div><div>Transition-metal dichalcogenide TiS<sub>2</sub> stands out as a sustainable candidate for room- and medium-temperature thermoelectric materials due to its affordability, non-toxicity, eco-friendly nature and use of non-critical elements. However, its light element compositional nature results in a large thermal conductivity, which is the main limitation of the thermoelectric performance of TiS<sub>2</sub>. Here, we report a multi-element doping strategy by incorporating equivalent (Se, Zr) elements and introducing higher-valence (Nb, Ta) and lower-valence (Y, La) elements in pairs to minimize its lattice thermal conductivity, <span><math><msub><mi>κ</mi><mtext>lat</mtext></msub></math></span>. The findings indicate a nearly 50 % decrease in <span><math><msub><mi>κ</mi><mtext>lat</mtext></msub></math></span> across the entire temperature range, attributed to the presence of strong point-defect scattering after multi-element doping. Additionally, we observed a reduced dependency of <span><math><msub><mi>κ</mi><mtext>lat</mtext></msub></math></span> on temperature in multi-element doped TiS<sub>2</sub>, as point defects can effectively scatter phonons at room temperature. As a result, the multi-element doped TiS<sub>2</sub> attained its highest <em>ZT</em> value of approximately 0.4 at 625 K. Incorporating higher-valence and lower-valence elements in pairs proves to be an effective method for decreasing lattice thermal conductivity without compromising too much of its large Seebeck coefficient.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120548"},"PeriodicalIF":8.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142588928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Thermal conductivity of WC: Microstructural design driven by first-principles simulations 碳化钨的导热性：第一原理模拟驱动的微结构设计

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-05 DOI: 10.1016/j.actamat.2024.120517

Samuel A. Humphry-Baker , Thomas A. Mellan , Mike Finnis , Peter Polcik , William E. Lee , Mike Reece , Salvatore Grasso

{"title":"Thermal conductivity of WC: Microstructural design driven by first-principles simulations","authors":"Samuel A. Humphry-Baker , Thomas A. Mellan , Mike Finnis , Peter Polcik , William E. Lee , Mike Reece , Salvatore Grasso","doi":"10.1016/j.actamat.2024.120517","DOIUrl":"10.1016/j.actamat.2024.120517","url":null,"abstract":"<div><div>The relationships between the microstructure and the thermal conductivity of binderless WC have been quantified, considering crystal orientation, isotopic abundance, porosity, and grain size. A significantly higher conductivity is predicted in the out-of-plane (c-axis) direction vs. the in-plane (a-axis) direction, using first principles simulations. Isotopic enrichment of the tungsten sublattice is predicted to increase conductivity, e.g., by a factor of 4–5 in the absence of boundary scattering. The results suggest that for an isotopically pure single crystal a thermal conductivity exceeding 1000 W m<sup>−1</sup> K<sup>−1</sup> may be achievable normal to the basal plane. The conductivity of samples with various porosities could be well fit by a minimum surface area (exponential) model, with a porosity exponent of <em>b</em> = 4.4. Experiment and simulation show a strong grain size dependence to conductivity below 1 µm, with a saturation beyond ∼10 µm. The experimental plateau values for <em>κ</em> were ∼45 % lower than those of the simulations due to deviations from perfect stoichiometry. We also find a higher scattering coefficient in the experiments, likely due to effects of grain size distribution and elongation. Our study clarifies the physical origin of disagreeing literature reports as being predominantly due to grain boundary scattering and enables microstructural design for thermally demanding environments.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120517"},"PeriodicalIF":8.3,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142580111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Constructing high-performance bulk thermoelectric composites by incorporating uniformly dispersed fullerene sub-nanoclusters 通过加入均匀分散的富勒烯亚纳米团簇构建高性能块状热电复合材料

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-05 DOI: 10.1016/j.actamat.2024.120540

Fanshi Wu , Yifan Shi , Wanjia Zhang , Wei Zhao , Hao Yang , Wenxin Lai , Yue Lou , Zhenhua Yan , Zhan Shi , Zhenhua Ge , Xiyang Wang , Liangwei Fu , Biao Xu

{"title":"Constructing high-performance bulk thermoelectric composites by incorporating uniformly dispersed fullerene sub-nanoclusters","authors":"Fanshi Wu , Yifan Shi , Wanjia Zhang , Wei Zhao , Hao Yang , Wenxin Lai , Yue Lou , Zhenhua Yan , Zhan Shi , Zhenhua Ge , Xiyang Wang , Liangwei Fu , Biao Xu","doi":"10.1016/j.actamat.2024.120540","DOIUrl":"10.1016/j.actamat.2024.120540","url":null,"abstract":"<div><div>Sub-nanomaterials possess unprecedented size-dependent properties compared to conventional nanomaterials, which endow them with great potential in catalysis, biomedicine, sensors, and so on. However, their applications in thermoelectrics are unknown due to poor thermal stability and low yields. Herein, we construct a series of thermoelectric composites by incorporating highly thermally stable and commercial fullerene sub-nanoclusters (C<sub>60</sub> or C<sub>70</sub>). We find that sub-nanoclusters as the second phase can conduce to optimized carrier concentration through charge transfer at interfaces while the carrier mobility is significantly enhanced due to atom orbital hybridization and size-dependent electrical scattering mechanism. Furthermore, the ultra-low thermal conductivity of C<sub>60</sub> due to its distorted chemical bonding and sub-nanometer pore, and the interfacial thermal resistance greatly suppress the phonon transport. Consequently, the 0.15 mol.% C<sub>60</sub>/Bi<sub>0.4</sub>Sb<sub>1.6</sub>Te<sub>3</sub> realizes an ultra-high <em>ZT</em> of ∼1.6 at 373 K, an excellent thermoelectric conversion efficiency of ∼7.4 %, and a huge cooling performance of ∼73 K. This work demonstrates the application of sub-nanomaterials in thermoelectrics and may shed light on other fields such as electronic devices, thermal management, and fullerene chemistry.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120540"},"PeriodicalIF":8.3,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142580008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhancing thermal stability of Nb nanowires in a NiTiFe matrix via texture engineering 通过纹理工程提高镍钛铁基体中铌纳米线的热稳定性

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-04 DOI: 10.1016/j.actamat.2024.120525

Yuxuan Chen , Yang Li , Suoqing Yu , Junsong Zhang , Shan Huang , Feihong Chu , Xiaobin Shi , Kaixuan Li , Zishu Lian , Daqiang Jiang , Yang Ren , Lishan Cui , Kaiyuan Yu

{"title":"Enhancing thermal stability of Nb nanowires in a NiTiFe matrix via texture engineering","authors":"Yuxuan Chen , Yang Li , Suoqing Yu , Junsong Zhang , Shan Huang , Feihong Chu , Xiaobin Shi , Kaixuan Li , Zishu Lian , Daqiang Jiang , Yang Ren , Lishan Cui , Kaiyuan Yu","doi":"10.1016/j.actamat.2024.120525","DOIUrl":"10.1016/j.actamat.2024.120525","url":null,"abstract":"<div><div>Metallic nanowires, renowned for their high strength and large elastic strain limits, have shown significant potential in rendering extraordinary structural and functional properties in composites. However, their integrity at high temperatures is often compromised due to fragmentation and spheroidization, processes driven by excess interfacial energy. Here, we demonstrate in a NiTiFe/Nb nanocomposite that the fragmentation and spheroidization of Nb nanowires can be significantly suppressed by tailoring the interfacial crystallographic orientation relationship between the nanowires and the matrix. By doping Fe into NiTi, we inhibit the typical deformation-induced amorphization of the NiTi-based matrix during severe deformation processing. The common (111)<sub>NiTi</sub>//(110)<sub>Nb</sub> texture is inherently suppressed and (110)<sub>NiTiFe</sub>//(110)<sub>Nb</sub> texture is formed instead. Such a change in texture allows Nb nanowires to retain their integrity up to 700 °C in the NiTiFe matrix, in contrast to the 550 °C in the counterparts. Simulation results indicate that the enhanced thermal stability of Nb nanowires is attributed to the reduced interfacial energy between (110)<sub>NiTiFe</sub> and (110)<sub>Nb</sub>. Additionally, Fe doping elevates the migration energy barrier for Nb diffusion, imposing further resistance to fragmentation and spheroidization.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120525"},"PeriodicalIF":8.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Improving strength and plasticity via pre-assembled dislocation networks in additively manufactured refractory high entropy alloy 通过预组装位错网络提高加成型难熔高熵合金的强度和塑性

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-04 DOI: 10.1016/j.actamat.2024.120526

Changxi Liu , Lai-Chang Zhang , Kuaishe Wang , Liqiang Wang

{"title":"Improving strength and plasticity via pre-assembled dislocation networks in additively manufactured refractory high entropy alloy","authors":"Changxi Liu , Lai-Chang Zhang , Kuaishe Wang , Liqiang Wang","doi":"10.1016/j.actamat.2024.120526","DOIUrl":"10.1016/j.actamat.2024.120526","url":null,"abstract":"<div><div>Refractory high entropy alloys (RHEAs), as a novel class of multi-principal element alloys, have attracted significant attention owing to their excellent properties. However, their low plasticity limits their potential applications, while the high melting points of the alloying elements face challenges to additive manufacturing (AM). Herein, RHEA, with extensively distributed cellular structure within their grains, was successfully fabricated using AM. Furthermore, we proposed a simple strategy to form a complete dislocation network within the cellular structure region in advance through cyclic deformation processing in the elastic stage (microplastic deformation). Dislocation networks are entangled with other dislocations, creating numerous pinned points adjacent cell walls, which impede dislocation motion. As a result, the cyclic deformation processing of RHEA achieves a yield strength of 1136 MPa while maintaining 50 % deformation strain without fracturing. The cyclic deformation processing method provides a route to strengthen additively manufactured alloys, offering a solution to overcome the trade-off between strength and plasticity.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120526"},"PeriodicalIF":8.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Interface compatibility and hysteresis in shape memory materials are affected by lattice distortions from applied stresses 形状记忆材料的界面兼容性和滞后性受外加应力造成的晶格畸变影响

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-11-04 DOI: 10.1016/j.actamat.2024.120528

Eliana M. Feygin , Christopher A. Schuh

{"title":"Interface compatibility and hysteresis in shape memory materials are affected by lattice distortions from applied stresses","authors":"Eliana M. Feygin , Christopher A. Schuh","doi":"10.1016/j.actamat.2024.120528","DOIUrl":"10.1016/j.actamat.2024.120528","url":null,"abstract":"<div><div>Significant effort has been put into designing shape-memory materials that can survive many cycles without functional or structural fatigue. A component of the design process is the condition defining perfect interface compatibility between the austenite and martensite lattices (λ<sub>2</sub> = 1). In this paper, we evaluate the traditional mathematical theories of martensite under applied stresses, which distort the lattice compatibility through elastic strains. In NiTi we find that elastic distortions resulting from applied stresses influence the interface compatibility to a degree of impacting the material's functional abilities. Combining our results with empirical relationships connecting interface compatibility to transformation hysteresis we show that the model matches reasonably to a number of experimental results in the literature in which hysteresis changes under applied loads. We also apply these theories to a shape-memory ceramic (zirconia), which suggests a large orientation-dependence and asymmetric behavior in tension and compression. In both systems, we find that variant selection plays a large role in whether interface compatibility will improve or worsen under stress.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120528"},"PeriodicalIF":8.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Discovery of collective nonjumping motions leading to Johari–Goldstein process of stress relaxation in model ionic glass 发现导致模型离子玻璃应力松弛的乔哈里-戈尔茨坦集体非跳跃运动过程

IF 9.4 1区材料科学

Acta Materialia Pub Date : 2024-11-04 DOI: 10.1016/j.actamat.2024.120536

Makina Saito, Takeaki Araki, Yohei Onodera, Koji Ohara, Makoto Seto, Yoshitaka Yoda, Yusuke Wakabayashi

{"title":"Discovery of collective nonjumping motions leading to Johari–Goldstein process of stress relaxation in model ionic glass","authors":"Makina Saito, Takeaki Araki, Yohei Onodera, Koji Ohara, Makoto Seto, Yoshitaka Yoda, Yusuke Wakabayashi","doi":"10.1016/j.actamat.2024.120536","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120536","url":null,"abstract":"The slow β, or Johari–Goldstein (JG) relaxation process, has been widely observed in glasses and is known to induce the stress relaxation associated with mechanical properties. So far, jumping motions of only a fraction of the particles were believed to contribute to the JG process in glass. However, there is no direct experimental evidence of the atomic-scale images due to the difficulties in microscopic observation. In this study, atomic motions in the quasi-spherical model ionic-glass-former Ca<sub>0.4</sub>K<sub>0.6</sub>(NO<sub>3</sub>)<sub>1.4</sub> were microscopically observed with one-angstrom resolution, the highest resolution to date, using X-ray time-domain interferometry. The microscopic experiment directly indicated that most particles underwent angstrom-scale motions in the time scale of the JG relaxation. This result was further supported by molecular dynamics (MD) simulations. A combined study of experiments and MD simulations revealed that most particles contributed to the JG process through unexpected collective nonjumping motions with angstrom-scale displacement, activated by jumping motions of a fraction of particles. The discovery of nonjumping motions by our atomic-scale dynamic observations has considerably advanced our understanding of the puzzling mechanism of the JG process.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"7 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0