Pub Date : 2025-04-09DOI: 10.1016/j.actamat.2025.121028
Jonathan Zimmerman, Eugen Rabkin
Recrystallization of metals plays a central role in materials processing as it represents a primary tool for manipulating material microstructure and properties. However, recrystallization has not yet been employed for the synthesis of metal nanoparticles. In this work we describe the kinetics of recrystallization and related annealing phenomena in Pt nanoparticles. We uniaxially deformed the particles and annealed them both in-situ and ex-situ while characterizing their morphology and microstructure. Our findings reveal that new grains often nucleate within the parent particle, only to be rapidly reabsorbed back into it, with a strong correlation between this phenomenon and particle size. We propose a model that combines recrystallization and recovery through dislocation annihilation at the particle surface, predicting a critical size for recrystallization in nanoparticles. Finally, we propose a set of rules for nanoparticle recrystallization, mirroring the rules of recrystallization in bulk materials.
{"title":"Nanoparticle recrystallization: kinetics and size-dependent behavior","authors":"Jonathan Zimmerman, Eugen Rabkin","doi":"10.1016/j.actamat.2025.121028","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121028","url":null,"abstract":"Recrystallization of metals plays a central role in materials processing as it represents a primary tool for manipulating material microstructure and properties. However, recrystallization has not yet been employed for the synthesis of metal nanoparticles. In this work we describe the kinetics of recrystallization and related annealing phenomena in Pt nanoparticles. We uniaxially deformed the particles and annealed them both <em>in-situ</em> and <em>ex-situ</em> while characterizing their morphology and microstructure. Our findings reveal that new grains often nucleate within the parent particle, only to be rapidly reabsorbed back into it, with a strong correlation between this phenomenon and particle size. We propose a model that combines recrystallization and recovery through dislocation annihilation at the particle surface, predicting a critical size for recrystallization in nanoparticles. Finally, we propose a set of rules for nanoparticle recrystallization, mirroring the rules of recrystallization in bulk materials.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"59 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143806497","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}
Space exploration demands lightweight high-performance permanent magnets that are fully functional in a wide temperature range of 2∼450 K. However, Nd-Fe-B permanent magnets, which have the strongest room-temperature magnetic properties, are unsuitable for such applications because of their degraded performance at both elevated and cryogenic temperatures. It is well-established that substituting praseodymium enhances the low-temperature properties of these magnets, while cobalt substitution improves high-temperature stability. However, using conventional manufacturing techniques, it is virtually impossible to replace more than 10% of iron with cobalt without a significant reduction in coercivity. Herein, we propose a non-equilibirum nanostructuring strategy, which is implemented by co-doping Pr and Co to attain a non-equilibrium microstructure with Co supersaturation in the matrix to overcome both the upper and lower temperature limitations. We constructed phase diagrams and operational temperature maps to determine the optimal composition and production temperature, resulting in a (Nd0.2Pr0.8)13.6(Fe0.75Co0.25)80.4Ga0.5B5.5 heavy-rare-earth-free permanent magnet with the desired properties. The operational temperature range is broadened from 135-350 K for ternary Nd-Fe-B magnets to 2-450 K for the (Nd0.2Pr0.8)13.6(Fe0.75Co0.25)80.4Ga0.5B5.5 magnet. The microstructural characterizations and micromagnetic simulations highlight the significance of non-equilibrium microstructures in this magnet, whereas the supersaturation of Co in the matrix and the suppression of unfavorable soft-magnetic phases are critical to realizing superior magnetic properties. The new non-equilibrium magnet plug the gap of high-performance magnet for space explorations, and the non-equilibrium nanostructuring strategy offers new possibilities for designing magnets with unprecedented properties.
太空探索需要在 2∼450 K 宽温度范围内完全正常工作的轻质高性能永磁体。然而，具有最强室温磁性能的钕铁硼永磁体不适合此类应用，因为它们在高温和低温下的性能都会下降。众所周知，用镨代替钕可增强这些磁体的低温特性，而用钴代替钕可提高高温稳定性。然而，使用传统制造技术，几乎不可能在不显著降低矫顽力的情况下用钴替代超过 10% 的铁。在此，我们提出了一种非平衡纳米结构策略，通过共掺杂镨和钴来实现基体中钴过饱和的非平衡微结构，从而克服温度上限和下限的限制。我们绘制了相图和工作温度图，以确定最佳成分和生产温度，从而生产出具有理想性能的 (Nd0.2Pr0.8)13.6(Fe0.75Co0.25)80.4Ga0.5B5.5 无重型稀土永磁体。工作温度范围从三元钕铁硼磁体的 135-350 K 到 (Nd0.2Pr0.8)13.6(Fe0.75Co0.25)80.4Ga0.5B5.5 磁体的 2-450 K。微结构表征和微磁模拟突出了非平衡微结构在这种磁体中的重要性，而基体中 Co 的过饱和以及不利软磁相的抑制是实现优异磁性能的关键。新型非平衡磁体填补了空间探索用高性能磁体的空白，而非平衡纳米结构策略则为设计具有前所未有特性的磁体提供了新的可能性。
{"title":"Non-equilibrium nanostructured permanent magnets with excellent magnetic properties over an exceptionally wide temperature range","authors":"Yuye Wu, Xuefeng Liao, Weiwei Zeng, Konstantin Skokov, Oliver Gutfleisch, Haichen Wu, Yuxiang Xiao, Yichen Xu, Xiaoxiao Wang, Keyu Yan, Yunquan Li, Hai-Tian Zhang, Qing Zhou, Ying Dong, Dazhuang Kang, Chengbao Jiang","doi":"10.1016/j.actamat.2025.121029","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121029","url":null,"abstract":"Space exploration demands lightweight high-performance permanent magnets that are fully functional in a wide temperature range of 2∼450 K. However, Nd-Fe-B permanent magnets, which have the strongest room-temperature magnetic properties, are unsuitable for such applications because of their degraded performance at both elevated and cryogenic temperatures. It is well-established that substituting praseodymium enhances the low-temperature properties of these magnets, while cobalt substitution improves high-temperature stability. However, using conventional manufacturing techniques, it is virtually impossible to replace more than 10% of iron with cobalt without a significant reduction in coercivity. Herein, we propose a non-equilibirum nanostructuring strategy, which is implemented by co-doping Pr and Co to attain a non-equilibrium microstructure with Co supersaturation in the matrix to overcome both the upper and lower temperature limitations. We constructed phase diagrams and operational temperature maps to determine the optimal composition and production temperature, resulting in a (Nd<sub>0.2</sub>Pr<sub>0.8</sub>)<sub>13.6</sub>(Fe<sub>0.75</sub>Co<sub>0.25</sub>)<sub>80.4</sub>Ga<sub>0.5</sub>B<sub>5.5</sub> heavy-rare-earth-free permanent magnet with the desired properties. The operational temperature range is broadened from 135-350 K for ternary Nd-Fe-B magnets to 2-450 K for the (Nd<sub>0.2</sub>Pr<sub>0.8</sub>)<sub>13.6</sub>(Fe<sub>0.75</sub>Co<sub>0.25</sub>)<sub>80.4</sub>Ga<sub>0.5</sub>B<sub>5.5</sub> magnet. The microstructural characterizations and micromagnetic simulations highlight the significance of non-equilibrium microstructures in this magnet, whereas the supersaturation of Co in the matrix and the suppression of unfavorable soft-magnetic phases are critical to realizing superior magnetic properties. The new non-equilibrium magnet plug the gap of high-performance magnet for space explorations, and the non-equilibrium nanostructuring strategy offers new possibilities for designing magnets with unprecedented properties.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"18 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143806495","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}
Pub Date : 2025-04-09DOI: 10.1016/j.actamat.2025.121023
Dongkyu Lee, Hyeokjoon June, Byeong-Gyu Park, Joo-Hee Kang, Taehyeong Kim, Jeong Woo Han, Hyungyu Jin
Two-step thermochemical water splitting (TWS) is a promising green hydrogen production technology in which metal oxides are used as redox-active materials to split steam. Among the several challenges toward the commercialization of two-step TWS, the limited performance of existing redox materials has been identified as a critical issue. Here, we report Fe-poor Ni ferrites (NFOs), a class of phase transformation oxides, as highly promising redox materials for two-step TWS that overcome the limitations of existing materials. These materials achieve a superior H2O-to-H2 conversion of 0.528 %/goxide under more favorable reaction conditions, outperforming state-of-the-art materials that exhibit < 0.250 %/goxide. A redox-active cation in Fe-poor NFOs is hypothesized and experimentally validated, establishing the fundamental structure-property relationships. Our results show that the extent of redox swing between the two active cations strongly correlates with water splitting performance. Density functional theory calculations reveal that both the number of active sites and the surface reaction energy play critical roles in determining the redox swing extent and, consequently, the water splitting performance. This study not only introduces Fe-poor NFOs as new state-of-the-art materials for two-step TWS, but also provides fundamental insights that can be broadly applied in the design of highly efficient redox oxides.
{"title":"Structural insights into iron-based phase transformation oxides for highly efficient thermochemical water splitting","authors":"Dongkyu Lee, Hyeokjoon June, Byeong-Gyu Park, Joo-Hee Kang, Taehyeong Kim, Jeong Woo Han, Hyungyu Jin","doi":"10.1016/j.actamat.2025.121023","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121023","url":null,"abstract":"Two-step thermochemical water splitting (TWS) is a promising green hydrogen production technology in which metal oxides are used as redox-active materials to split steam. Among the several challenges toward the commercialization of two-step TWS, the limited performance of existing redox materials has been identified as a critical issue. Here, we report Fe-poor Ni ferrites (NFOs), a class of phase transformation oxides, as highly promising redox materials for two-step TWS that overcome the limitations of existing materials. These materials achieve a superior H<sub>2</sub>O-to-H<sub>2</sub> conversion of 0.528 %/g<sub>oxide</sub> under more favorable reaction conditions, outperforming state-of-the-art materials that exhibit < 0.250 %/g<sub>oxide</sub>. A redox-active cation in Fe-poor NFOs is hypothesized and experimentally validated, establishing the fundamental structure-property relationships. Our results show that the extent of redox swing between the two active cations strongly correlates with water splitting performance. Density functional theory calculations reveal that both the number of active sites and the surface reaction energy play critical roles in determining the redox swing extent and, consequently, the water splitting performance. This study not only introduces Fe-poor NFOs as new state-of-the-art materials for two-step TWS, but also provides fundamental insights that can be broadly applied in the design of highly efficient redox oxides.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"183 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143806496","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}
The yield strength and ductility of nanoscale biphasic materials are governed by the critical resolved shear stress (CRSS) for dislocation nucleation. Polysynthetic twinned (PST) TiAl single crystals with alternating layers of γ-TiAl and α<sub>2</sub>-Ti<sub>3</sub>Al exhibit high yield strength and ductility at room temperature. However, the relationship between its high performance and dislocation nucleation mechanism has not been clearly understood. In this work, we investigated the influence of the interfacial dislocations and the normal stress of slip plane on dislocation nucleation in the γ-TiAl/α<sub>2</sub>-Ti<sub>3</sub>Al alloys via biaxial loading using molecular dynamics simulations. Three types of dislocations were observed in the initial yielding stage, including <span><span style=""></span><span data-mathml='<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow is="true"><mrow is="true"><mo is="true">{</mo><mn is="true">111</mn><mo is="true">}</mo></mrow><mo linebreak="goodbreak" is="true"><</mo><mn is="true">11</mn><mover accent="true" is="true"><mn is="true">2</mn><mo is="true">¯</mo></mover><mrow is="true"><mo is="true">]</mo></mrow></mrow></math>' role="presentation" style="font-size: 90%; display: inline-block; position: relative;" tabindex="0"><svg aria-hidden="true" focusable="false" height="2.779ex" role="img" style="vertical-align: -0.812ex;" viewbox="0 -846.5 5686.6 1196.3" width="13.208ex" xmlns:xlink="http://www.w3.org/1999/xlink"><g fill="currentColor" stroke="currentColor" stroke-width="0" transform="matrix(1 0 0 -1 0 0)"><g is="true"><g is="true"><g is="true"><use xlink:href="#MJMAIN-7B"></use></g><g is="true" transform="translate(500,0)"><use xlink:href="#MJMAIN-31"></use><use x="500" xlink:href="#MJMAIN-31" y="0"></use><use x="1001" xlink:href="#MJMAIN-31" y="0"></use></g><g is="true" transform="translate(2002,0)"><use xlink:href="#MJMAIN-7D"></use></g></g><g is="true" transform="translate(2780,0)"><use xlink:href="#MJMAIN-3C"></use></g><g is="true" transform="translate(3836,0)"><use xlink:href="#MJMAIN-31"></use><use x="500" xlink:href="#MJMAIN-31" y="0"></use></g><g is="true" transform="translate(4837,0)"><g is="true" transform="translate(35,0)"><use xlink:href="#MJMAIN-32"></use></g><g is="true" transform="translate(0,198)"><use x="-70" xlink:href="#MJMAIN-AF" y="0"></use><use x="70" xlink:href="#MJMAIN-AF" y="0"></use></g></g><g is="true" transform="translate(5408,0)"><use is="true" xlink:href="#MJMAIN-5D"></use></g></g></g></svg><span role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow is="true"><mrow is="true"><mo is="true">{</mo><mn is="true">111</mn><mo is="true">}</mo></mrow><mo is="true" linebreak="goodbreak"><</mo><mn is="true">11</mn><mover accent="true" is="true"><mn is="true">2</mn><mo is="true">¯</mo></mo
{"title":"Designing high ductility TiAl alloys based on dislocation nucleation mechanism","authors":"Shiping Wang, Demin Zhu, Zhongtao Lu, Xiaobin Feng, Wenjuan Li, Pengcheng Zhai, Yang Chen, Guodong Li, Zhixiang Qi, Guang Chen","doi":"10.1016/j.actamat.2025.121027","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121027","url":null,"abstract":"The yield strength and ductility of nanoscale biphasic materials are governed by the critical resolved shear stress (CRSS) for dislocation nucleation. Polysynthetic twinned (PST) TiAl single crystals with alternating layers of γ-TiAl and α<sub>2</sub>-Ti<sub>3</sub>Al exhibit high yield strength and ductility at room temperature. However, the relationship between its high performance and dislocation nucleation mechanism has not been clearly understood. In this work, we investigated the influence of the interfacial dislocations and the normal stress of slip plane on dislocation nucleation in the γ-TiAl/α<sub>2</sub>-Ti<sub>3</sub>Al alloys via biaxial loading using molecular dynamics simulations. Three types of dislocations were observed in the initial yielding stage, including <span><span style=\"\"></span><span data-mathml='<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow is=\"true\"><mrow is=\"true\"><mo is=\"true\">{</mo><mn is=\"true\">111</mn><mo is=\"true\">}</mo></mrow><mo linebreak=\"goodbreak\" is=\"true\">&lt;</mo><mn is=\"true\">11</mn><mover accent=\"true\" is=\"true\"><mn is=\"true\">2</mn><mo is=\"true\">&#xAF;</mo></mover><mrow is=\"true\"><mo is=\"true\">]</mo></mrow></mrow></math>' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"><svg aria-hidden=\"true\" focusable=\"false\" height=\"2.779ex\" role=\"img\" style=\"vertical-align: -0.812ex;\" viewbox=\"0 -846.5 5686.6 1196.3\" width=\"13.208ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"><g is=\"true\"><g is=\"true\"><g is=\"true\"><use xlink:href=\"#MJMAIN-7B\"></use></g><g is=\"true\" transform=\"translate(500,0)\"><use xlink:href=\"#MJMAIN-31\"></use><use x=\"500\" xlink:href=\"#MJMAIN-31\" y=\"0\"></use><use x=\"1001\" xlink:href=\"#MJMAIN-31\" y=\"0\"></use></g><g is=\"true\" transform=\"translate(2002,0)\"><use xlink:href=\"#MJMAIN-7D\"></use></g></g><g is=\"true\" transform=\"translate(2780,0)\"><use xlink:href=\"#MJMAIN-3C\"></use></g><g is=\"true\" transform=\"translate(3836,0)\"><use xlink:href=\"#MJMAIN-31\"></use><use x=\"500\" xlink:href=\"#MJMAIN-31\" y=\"0\"></use></g><g is=\"true\" transform=\"translate(4837,0)\"><g is=\"true\" transform=\"translate(35,0)\"><use xlink:href=\"#MJMAIN-32\"></use></g><g is=\"true\" transform=\"translate(0,198)\"><use x=\"-70\" xlink:href=\"#MJMAIN-AF\" y=\"0\"></use><use x=\"70\" xlink:href=\"#MJMAIN-AF\" y=\"0\"></use></g></g><g is=\"true\" transform=\"translate(5408,0)\"><use is=\"true\" xlink:href=\"#MJMAIN-5D\"></use></g></g></g></svg><span role=\"presentation\"><math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow is=\"true\"><mrow is=\"true\"><mo is=\"true\">{</mo><mn is=\"true\">111</mn><mo is=\"true\">}</mo></mrow><mo is=\"true\" linebreak=\"goodbreak\"><</mo><mn is=\"true\">11</mn><mover accent=\"true\" is=\"true\"><mn is=\"true\">2</mn><mo is=\"true\">¯</mo></mo","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"28 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143798367","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}
Pub Date : 2025-04-08DOI: 10.1016/j.actamat.2025.120995
Anthony Nakhoul , Alixe Dreano , Claire Maurice , Vincent Barnier , Matthieu Lenci , Florence Garrelie , Jean-Philippe Colombier , Frédéric Christien
The increasing use of hydrogen as an energy carrier necessitates ensuring the mechanical integrity of systems exposed to hydrogenated environments. In this context, surface engineering is crucial for reducing hydrogen ingress into metallic materials. This study explores the use of ultrafast laser texturing on a Fe-Cr alloy to create hydrogen-resistant surfaces. Two distinct laser-induced periodic surface structures (LIPSS) were performed: low spatial frequency laser texturing (LSFL) and high spatial frequency laser texturing (HSFL). Hydrogen uptake was evaluated through electrochemical permeation on the textured surfaces and compared to a mirror-like (Mirror) surface. Results showed significant reduction in hydrogen subsurface concentration by 89% for LSFL and 95% for HSFL, highlighting the potential of this technology for developing hydrogen-resistant surfaces. To further elucidate the mechanisms, this study decoupled the effects of oxide layers, surface topography, and subsurface defects on hydrogen uptake. Experimental investigations using X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM) revealed that the ultra-thin oxide layer formed during laser texturing plays a pivotal role in mitigating hydrogen absorption. The impact of surface topography was investigated using Atomic Force Microscopy (AFM). It appears that high skewness and kurtosis reduce hydrogen permeation by 40% in HSFL compared to LSFL topography. These findings underscore the effectiveness of ultrafast laser texturing in controlling hydrogen uptake in Fe-Cr alloys, with potential implications for enhancing the durability and performance of industrial materials.
{"title":"Periodic laser surface texturing limits hydrogen ingress in Fe-Cr alloy","authors":"Anthony Nakhoul , Alixe Dreano , Claire Maurice , Vincent Barnier , Matthieu Lenci , Florence Garrelie , Jean-Philippe Colombier , Frédéric Christien","doi":"10.1016/j.actamat.2025.120995","DOIUrl":"10.1016/j.actamat.2025.120995","url":null,"abstract":"<div><div>The increasing use of hydrogen as an energy carrier necessitates ensuring the mechanical integrity of systems exposed to hydrogenated environments. In this context, surface engineering is crucial for reducing hydrogen ingress into metallic materials. This study explores the use of ultrafast laser texturing on a Fe-Cr alloy to create hydrogen-resistant surfaces. Two distinct laser-induced periodic surface structures (LIPSS) were performed: low spatial frequency laser texturing (LSFL) and high spatial frequency laser texturing (HSFL). Hydrogen uptake was evaluated through electrochemical permeation on the textured surfaces and compared to a mirror-like (Mirror) surface. Results showed significant reduction in hydrogen subsurface concentration by 89% for LSFL and 95% for HSFL, highlighting the potential of this technology for developing hydrogen-resistant surfaces. To further elucidate the mechanisms, this study decoupled the effects of oxide layers, surface topography, and subsurface defects on hydrogen uptake. Experimental investigations using X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM) revealed that the ultra-thin oxide layer formed during laser texturing plays a pivotal role in mitigating hydrogen absorption. The impact of surface topography was investigated using Atomic Force Microscopy (AFM). It appears that high skewness and kurtosis reduce hydrogen permeation by 40% in HSFL compared to LSFL topography. These findings underscore the effectiveness of ultrafast laser texturing in controlling hydrogen uptake in Fe-Cr alloys, with potential implications for enhancing the durability and performance of industrial materials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"291 ","pages":"Article 120995"},"PeriodicalIF":8.3,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143797637","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}
Pub Date : 2025-04-08DOI: 10.1016/j.actamat.2025.121024
Huacui Wang, Binghe Liu, Dongjiang Li, Jun Xu
The cathode in lithium-ion batteries (LIBs) is invariably subjected to mechanical stress due to external packaging constraints, and internal ionic diffusion and particle phase change. The (de)lithiation in lithium iron phosphate (LiFePO4) occurs through the growth of a two-phase front with a fixed activity, thereby producing a relatively flat (dis)charge curve, posing a grand challenge for the battery status estimation. This knowledge gap not only hinders our understanding of the relationship between mechanics and electrochemical behavior but also limits the potential for leveraging mechanical regulation in the development of high-performance electrode materials and cells. To address this issue, we quantitatively investigate the stress effects on the LiFePO4 cathode by employing constant current charge/discharge processes to capture the electrochemical performance of LIBs. To further understand the underlying mechanism and establish a new electrochemo-mechanics coupling model, comprehensive electrochemical characterizations upon various external stress statuses are conducted. Our findings reveal that within the 0-0.9 MPa range of external compressive stress, LiFePO4 cathodes exhibit enhanced ionic diffusion coefficients, improved nucleation kinetics and reversibility, although accompanied by a small reduction in the cathode's equilibrium potential. In-situ X-ray diffraction experiments under diverse stress conditions corroborate the beneficial effects of mechanical stress on electrode reactions. These insights offer critical knowledge and pave the way for improved performance, reliability, and durability.
{"title":"Mechanistic Analysis on Electrochemo-mechanics Behaviors of Lithium Iron Phosphate Cathodes","authors":"Huacui Wang, Binghe Liu, Dongjiang Li, Jun Xu","doi":"10.1016/j.actamat.2025.121024","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121024","url":null,"abstract":"The cathode in lithium-ion batteries (LIBs) is invariably subjected to mechanical stress due to external packaging constraints, and internal ionic diffusion and particle phase change. The (de)lithiation in lithium iron phosphate (LiFePO<sub>4</sub>) occurs through the growth of a two-phase front with a fixed activity, thereby producing a relatively flat (dis)charge curve, posing a grand challenge for the battery status estimation. This knowledge gap not only hinders our understanding of the relationship between mechanics and electrochemical behavior but also limits the potential for leveraging mechanical regulation in the development of high-performance electrode materials and cells. To address this issue, we quantitatively investigate the stress effects on the LiFePO<sub>4</sub> cathode by employing constant current charge/discharge processes to capture the electrochemical performance of LIBs. To further understand the underlying mechanism and establish a new electrochemo-mechanics coupling model, comprehensive electrochemical characterizations upon various external stress statuses are conducted. Our findings reveal that within the 0-0.9 MPa range of external compressive stress, LiFePO<sub>4</sub> cathodes exhibit enhanced ionic diffusion coefficients, improved nucleation kinetics and reversibility, although accompanied by a small reduction in the cathode's equilibrium potential. <em>In-situ</em> X-ray diffraction experiments under diverse stress conditions corroborate the beneficial effects of mechanical stress on electrode reactions. These insights offer critical knowledge and pave the way for improved performance, reliability, and durability.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"183 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143797635","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}
Ultra-high strength steels with exceptional mechanical properties and corrosion resistance are increasingly critical in energy, aerospace, and biomedical applications. This study introduces a novel antibacterial Fe‒Ni‒Co‒Cr‒Ti‒Mo ultra-high strength steel, enhanced with Cu alloying, achieving a strength of approximately 1.8 GPa. We conducted a comprehensive investigation into the effects of Cu on tensile properties, antibacterial efficacy, and corrosion resistance at the atomic scale. Our findings reveal that Cu addition promotes the co-precipitation of Cu-rich and Ni3Ti nano precipitates, which not only enhances the strength of the steel, but also provides heterogeneous nucleation sites for the reversion of austenite, resulting in improved uniform elongation. Moreover, the high density of Cu-rich precipitates disrupts the passive layer on the steel surface, facilitating the release of Cu²⁺ ions that penetrate and damage bacterial colonies, demonstrating effectiveness in reducing sulfate-reducing bacteria (SRB) related degradation. Additionally, the presence of Cu enhances the corrosion resistance by inhibiting the formation of (Cr,Mo)-enriched clusters, which promotes the development of a more continuous and adherent passive layer to mitigate localized pitting corrosion caused by SRB. These findings highlight the triple roles of Cu-rich nano precipitates in enhancing tensile properties, antibacterial efficacy, and corrosion resistance, presenting a promising strategy for extending the durability of steels in SRB-prone industrial environments.
{"title":"Cu-rich nano precipitates simultaneously enhance the tensile properties, antibacterial efficacy, and corrosion resistance of ultra-high strength steel","authors":"Boxin Wei, Mengchao Niu, Zheng Cai, Jin Xu, Cheng Sun, Wei Wang, Zhongji Sun, Tangqing Wu, Upadrasta Ramamurty","doi":"10.1016/j.actamat.2025.121026","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121026","url":null,"abstract":"Ultra-high strength steels with exceptional mechanical properties and corrosion resistance are increasingly critical in energy, aerospace, and biomedical applications. This study introduces a novel antibacterial Fe‒Ni‒Co‒Cr‒Ti‒Mo ultra-high strength steel, enhanced with Cu alloying, achieving a strength of approximately 1.8 GPa. We conducted a comprehensive investigation into the effects of Cu on tensile properties, antibacterial efficacy, and corrosion resistance at the atomic scale. Our findings reveal that Cu addition promotes the co-precipitation of Cu-rich and Ni<sub>3</sub>Ti nano precipitates, which not only enhances the strength of the steel, but also provides heterogeneous nucleation sites for the reversion of austenite, resulting in improved uniform elongation. Moreover, the high density of Cu-rich precipitates disrupts the passive layer on the steel surface, facilitating the release of Cu²⁺ ions that penetrate and damage bacterial colonies, demonstrating effectiveness in reducing sulfate-reducing bacteria (SRB) related degradation. Additionally, the presence of Cu enhances the corrosion resistance by inhibiting the formation of (Cr,Mo)-enriched clusters, which promotes the development of a more continuous and adherent passive layer to mitigate localized pitting corrosion caused by SRB. These findings highlight the triple roles of Cu-rich nano precipitates in enhancing tensile properties, antibacterial efficacy, and corrosion resistance, presenting a promising strategy for extending the durability of steels in SRB-prone industrial environments.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"19 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143798372","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}
Pub Date : 2025-04-08DOI: 10.1016/j.actamat.2025.120992
Emma Radice, Marco Salvalaglio, Roberto Bergamaschini
We present a phase-field model for simulating the solid-state dewetting of anisotropic crystalline films on non-planar substrates. This model exploits two order parameters to trace implicitly the crystal free surface and the substrate profile in both two and three dimensions. First, we validate the model by comparing numerical simulation results for planar substrates with those obtained by a conventional phase-field approach and by assessing the convergence toward the equilibrium shape predicted by the Winterbottom construction. We then explore non-planar geometries, examining the combined effects of surface-energy anisotropies and parameters controlling the contact angle. Our findings reveal that crystalline particles on curved supports lose self-similarity and exhibit a volume-dependent apparent contact angle, with opposite trends for convex versus concave profiles. Additionally, we investigate the migration of faceted particles on substrates with variable curvature. Applying this model to experimentally relevant cases like spheroidal and pit-patterned substrates demonstrates various behaviors that could be leveraged to direct self-assembly of nanostructures, from ordered nanoparticles to interconnected networks with complex topology.
{"title":"Phase-field modelling of anisotropic solid-state dewetting on patterned substrates","authors":"Emma Radice, Marco Salvalaglio, Roberto Bergamaschini","doi":"10.1016/j.actamat.2025.120992","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120992","url":null,"abstract":"We present a phase-field model for simulating the solid-state dewetting of anisotropic crystalline films on non-planar substrates. This model exploits two order parameters to trace implicitly the crystal free surface and the substrate profile in both two and three dimensions. First, we validate the model by comparing numerical simulation results for planar substrates with those obtained by a conventional phase-field approach and by assessing the convergence toward the equilibrium shape predicted by the Winterbottom construction. We then explore non-planar geometries, examining the combined effects of surface-energy anisotropies and parameters controlling the contact angle. Our findings reveal that crystalline particles on curved supports lose self-similarity and exhibit a volume-dependent apparent contact angle, with opposite trends for convex versus concave profiles. Additionally, we investigate the migration of faceted particles on substrates with variable curvature. Applying this model to experimentally relevant cases like spheroidal and pit-patterned substrates demonstrates various behaviors that could be leveraged to direct self-assembly of nanostructures, from ordered nanoparticles to interconnected networks with complex topology.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"96 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143798095","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}
Pub Date : 2025-04-07DOI: 10.1016/j.actamat.2025.120993
Nina Prakash, Paul Gasper, Francois Usseglio-Viretta
Semantic segmentation is a critical step in microscopy analysis to enable quantification of sample properties or to run structurally-resolved physics-based simulations. Machine learning has emerged as a viable alternative to traditional segmentation approaches like thresholding or watershed segmentation due to its noise tolerance and ability to perform shape- and texture-based segmentation. However, traditional methods still maintain an advantage by allowing for the explicit incorporation of domain knowledge that may be known a priori or measured ex situ, for example, enforcing that the volume fractions of phases from the segmentation match known values. In comparison, machine learning methods for semantic segmentation in the materials domain, which are limited by sparsely available hand-labels for model training, cannot explicitly incorporate domain knowledge into the classification problem, limiting their trustability and explainability. Here, we develop new regularization loss terms that incorporate domain knowledge into the training of a tree-based machine learning classification model, and demonstrate that the predicted segmentation can be tuned without modifying the training labels. The loss terms presented here enable targeting of specific volume fractions for the predicted phases as well as maximizing or minimizing the connectivity of a target phase. This method provides materials researchers additional knobs to tune the output of a machine learning-based segmentation model, leveraging the capabilities of machine-learned segmentation models while enabling domain knowledge to be explicitly incorporated into the model training process.
{"title":"ExpertSegmentation: Segmentation for microscopy with domain-informed targets via custom loss","authors":"Nina Prakash, Paul Gasper, Francois Usseglio-Viretta","doi":"10.1016/j.actamat.2025.120993","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120993","url":null,"abstract":"Semantic segmentation is a critical step in microscopy analysis to enable quantification of sample properties or to run structurally-resolved physics-based simulations. Machine learning has emerged as a viable alternative to traditional segmentation approaches like thresholding or watershed segmentation due to its noise tolerance and ability to perform shape- and texture-based segmentation. However, traditional methods still maintain an advantage by allowing for the explicit incorporation of domain knowledge that may be known a priori or measured ex situ, for example, enforcing that the volume fractions of phases from the segmentation match known values. In comparison, machine learning methods for semantic segmentation in the materials domain, which are limited by sparsely available hand-labels for model training, cannot explicitly incorporate domain knowledge into the classification problem, limiting their trustability and explainability. Here, we develop new regularization loss terms that incorporate domain knowledge into the training of a tree-based machine learning classification model, and demonstrate that the predicted segmentation can be tuned without modifying the training labels. The loss terms presented here enable targeting of specific volume fractions for the predicted phases as well as maximizing or minimizing the connectivity of a target phase. This method provides materials researchers additional knobs to tune the output of a machine learning-based segmentation model, leveraging the capabilities of machine-learned segmentation models while enabling domain knowledge to be explicitly incorporated into the model training process.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"37 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143798370","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}
Pub Date : 2025-04-06DOI: 10.1016/j.actamat.2025.121021
Ramandeep Mandia, Mohamadali Malakoutian, Kelly Woo, Manuel A. Roldan, Srabanti Chowdhury, David J. Smith
Interfaces between polycrystalline (PC) diamond and Si substrates with thin dielectric interlayers of SiO2 or SiC were studied at the atomic scale to understand the impact of the interlayer on phonon transitions from one material to the other. Our previous thermal characterization study had revealed that the dielectric interlayer led to significant reductions in the thermal boundary resistance (TBR) between diamond and Si for both interlayer types. However, the structural and chemical data needed to fully understand the underlying reason(s) for these reductions were unavailable. High-resolution scanning transmission electron microscopy and electron-energy-loss spectroscopy were used here to analyze the structural and chemical transitions within the PC-diamond/interlayer/Si heterostructures, and to correlate these observations with the trends in measured TBR values. The non-abrupt interface observed between PC-diamond and SiO2 interlayers caused by intermixing of Si, C, and O during growth of the diamond layer, and the gradual changes in the Si:C ratio in SiC interlayers, appear to facilitate smooth phonon mode transitions in both cases. The SiO2 interlayers exhibited the anticipated trend in TBR as a function of interlayer thickness, whereas the SiC interlayers deviated substantially from expectations, most likely due to gradual variations in the Si:C ratio and the unexpected presence of SiC nanocrystallites within the interlayer. Despite the presence of these nanocrystallites, the substantial reduction of 70% in TBR value compared to an abrupt interface, is still significant. Overall, these results confirm that interlayer engineering offers a viable route towards thermal management in compact high-power electronic devices.
{"title":"Structural and chemical transitions in diamond/dielectric/Si heterostructures","authors":"Ramandeep Mandia, Mohamadali Malakoutian, Kelly Woo, Manuel A. Roldan, Srabanti Chowdhury, David J. Smith","doi":"10.1016/j.actamat.2025.121021","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121021","url":null,"abstract":"Interfaces between polycrystalline (PC) diamond and Si substrates with thin dielectric interlayers of SiO<sub>2</sub> or SiC were studied at the atomic scale to understand the impact of the interlayer on phonon transitions from one material to the other. Our previous thermal characterization study had revealed that the dielectric interlayer led to significant reductions in the thermal boundary resistance (TBR) between diamond and Si for both interlayer types. However, the structural and chemical data needed to fully understand the underlying reason(s) for these reductions were unavailable. High-resolution scanning transmission electron microscopy and electron-energy-loss spectroscopy were used here to analyze the structural and chemical transitions within the PC-diamond/interlayer/Si heterostructures, and to correlate these observations with the trends in measured TBR values. The non-abrupt interface observed between PC-diamond and SiO<sub>2</sub> interlayers caused by intermixing of Si, C, and O during growth of the diamond layer, and the gradual changes in the Si:C ratio in SiC interlayers, appear to facilitate smooth phonon mode transitions in both cases. The SiO<sub>2</sub> interlayers exhibited the anticipated trend in TBR as a function of interlayer thickness, whereas the SiC interlayers deviated substantially from expectations, most likely due to gradual variations in the Si:C ratio and the unexpected presence of SiC nanocrystallites within the interlayer. Despite the presence of these nanocrystallites, the substantial reduction of 70% in TBR value compared to an abrupt interface, is still significant. Overall, these results confirm that interlayer engineering offers a viable route towards thermal management in compact high-power electronic devices.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"24 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784819","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}
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