Acta Materialia最新文献_第6页

Interfacial atomic vibration: A key dynamic characteristic for heterogeneous nucleation substrates 界面原子振动：非均相成核基底的关键动态特性

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-19 DOI: 10.1016/j.actamat.2026.121948

Dayong Wu , Liuke Zhen , Sida Ma , Yameng Guo , Haikun Ma , Jie Kang , Wang Li , Qian Wang , Huicong Dong , Yandong Wang , Hongbiao Dong , Ru Su

Heterogeneous nucleation during metal solidification is a key pathway for achieving grain refinement. However, due to the challenges in experimentally probing the solid-liquid interface, the underlying atomistic mechanisms remain unclear. Although classical lattice matching theories provide a framework for geometric compatibility, the static rigid models inherently neglect the strong atomic dynamics characteristic of high-temperature interfaces. In this study, ab initio molecular dynamics (AIMD) with on-the-fly machine learning force field (MLFF) is applied to evaluate the templating efficiency of different potential substrates for Al alloys. The templating efficiency is defined here as the capability to induce structural ordering within the pre-nucleation layer (PNL). The results show that a deep interfacial potential well (E_w) provides the necessary driving force to localize liquid atoms, whereas excessive atomic vibrations spatially disrupt this ordering process. The effect of temperature prompts the integration of interface dynamics into geometric mismatch. The dynamic stability is the main prerequisite for the initial PNL formation near the liquidus, and the epitaxial growth of PNL into stable nuclei is constrained by the accumulated lattice strain as the temperature decreases. Based on this dynamic-static mechanism and engineering considerations, a (Ta, Ti)B₂/Al₃Ta substrate is designed, which achieves significant grain refinement in Al-Si alloys. These findings deepen the understanding of heterogeneous nucleation and highlight interfacial dynamics as an important factor for the design of nucleation substrates.

金属凝固过程中的非均相形核是实现晶粒细化的重要途径。然而，由于实验探测固液界面的挑战，潜在的原子机制仍然不清楚。尽管经典的晶格匹配理论为几何相容性提供了一个框架，但静态刚性模型固有地忽略了高温界面的强原子动力学特性。本研究采用从头算分子动力学（AIMD）与动态机器学习力场（MLFF）相结合的方法，对不同潜在基底的铝合金模板效率进行了评价。模板效率在这里定义为在预成核层（PNL）内诱导结构有序的能力。结果表明，深层界面势阱（Ew）为液体原子的定域提供了必要的驱动力，而过度的原子振动在空间上破坏了这一有序过程。温度的影响促使界面动力学集成到几何失配中。动态稳定性是液相线附近初始PNL形成的主要前提，随着温度的降低，PNL外延向稳定核的生长受到晶格应变累积的限制。基于这一动态静态机理和工程考虑，设计了一种（Ta, Ti）B2/Al3Ta衬底，使Al-Si合金晶粒细化。这些发现加深了对非均相成核的理解，并强调界面动力学是设计成核底物的重要因素。

{"title":"Interfacial atomic vibration: A key dynamic characteristic for heterogeneous nucleation substrates","authors":"Dayong Wu , Liuke Zhen , Sida Ma , Yameng Guo , Haikun Ma , Jie Kang , Wang Li , Qian Wang , Huicong Dong , Yandong Wang , Hongbiao Dong , Ru Su","doi":"10.1016/j.actamat.2026.121948","DOIUrl":"10.1016/j.actamat.2026.121948","url":null,"abstract":"<div><div>Heterogeneous nucleation during metal solidification is a key pathway for achieving grain refinement. However, due to the challenges in experimentally probing the solid-liquid interface, the underlying atomistic mechanisms remain unclear. Although classical lattice matching theories provide a framework for geometric compatibility, the static rigid models inherently neglect the strong atomic dynamics characteristic of high-temperature interfaces. In this study, <em>ab initio</em> molecular dynamics (AIMD) with on-the-fly machine learning force field (MLFF) is applied to evaluate the templating efficiency of different potential substrates for Al alloys. The templating efficiency is defined here as the capability to induce structural ordering within the pre-nucleation layer (PNL). The results show that a deep interfacial potential well (<em>E<sub>w</sub></em>) provides the necessary driving force to localize liquid atoms, whereas excessive atomic vibrations spatially disrupt this ordering process. The effect of temperature prompts the integration of interface dynamics into geometric mismatch. The dynamic stability is the main prerequisite for the initial PNL formation near the liquidus, and the epitaxial growth of PNL into stable nuclei is constrained by the accumulated lattice strain as the temperature decreases. Based on this dynamic-static mechanism and engineering considerations, a (Ta, Ti)B<sub>2</sub>/Al<sub>3</sub>Ta substrate is designed, which achieves significant grain refinement in Al-Si alloys. These findings deepen the understanding of heterogeneous nucleation and highlight interfacial dynamics as an important factor for the design of nucleation substrates.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121948"},"PeriodicalIF":9.3,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146000672","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

Flash sintering in oxides: The Debye temperature is not the limit 在氧化物中闪烧：德拜温度不是极限

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-17 DOI: 10.1016/j.actamat.2026.121945

Daniil Lewin, Doru C. Lupascu

Herein, we investigate the onset behavior of flash sintering, a rather novel material processing method. A thermal runaway driven by Joule heating has established itself as the likely explanation for the general onset behavior of flash sintering, however, multiple experimental observations appear to directly contradict this idea. One such observation is that the material specific Debye temperature appears to be the lowest temperature at which the onset of flash sintering is possible in oxides. In this work, we test this Debye limit of flash sintering on barium titanate (BaTiO₃), strontium titanate (SrTiO₃), cobalt ferrite (CoFe₂O₄), copper oxide (CuO), and titanium trioxide (Ti₂O₃) and ultimately refute it. Furthermore, we apply a basic modelling approach to investigate whether the onset behavior of flash sintering at high electric fields can be explained by Joule heating alone. We apply our findings to data from the original studies and propose an alternative interpretation to the previously inferred hard limit at the Debye temperature.

在此，我们研究了闪速烧结的开始行为，这是一种相当新颖的材料加工方法。由焦耳加热驱动的热失控已经确立了自己作为闪速烧结一般开始行为的可能解释，然而，多个实验观察似乎直接与这一想法相矛盾。其中一个观察结果是，材料特定的德拜温度似乎是氧化物中可能发生闪烧的最低温度。在这项工作中，我们测试了钛酸钡（BaTiO3）、钛酸锶（SrTiO3）、钴铁氧体（CoFe2O4）、氧化铜（CuO）和三氧化钛（Ti2O3）的闪烧Debye极限，并最终反驳了它。此外，我们应用了一个基本的建模方法来研究是否可以用焦耳加热单独解释高电场下闪烧的开始行为。我们将我们的发现应用于原始研究的数据，并对先前推断的德拜温度硬极限提出了另一种解释。

引用次数: 0

Thermodynamics of compositionally complex (“high-entropy”) oxides – A-site mixed (5R0.2)CoO3-δ (R = rare-earth element) perovskite-type cobaltites 复合（“高熵”）氧化物的热力学- a位混合（5R0.2）CoO3-δ （R =稀土元素）钙钛矿型钴酸盐

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-16 DOI: 10.1016/j.actamat.2026.121943

Vladimir V. Sereda , Dmitry S. Tsvetkov , Anna V. Sereda , Dmitry A. Malyshkin , Ivan L. Ivanov , Irina A. Bajenova , Semen S. Kuzovchikov , Alexandra V. Khvan , Andrey Yu. Zuev

Due to their unique magnetic and electronic properties, materials based on rare-earth perovskite-type cobaltites are promising for electronic and energy conversion applications. In this study, several single-phase cobaltites (5R_0.2)CoO_3-δ with five different rare-earth elements R in the A-sublattice were synthesized via the glycerol-nitrate technique. X-ray diffraction (XRD) confirmed the orthorhombic (Pnma) perovskite structure of (5R_0.2)CoO_3-δ, and energy-dispersive microanalysis showed a uniform cation distribution in these oxides. The heat capacity of (5R_0.2)CoO_3-δ was investigated using differential scanning calorimetry, and the enthalpy of formation was determined via reduction reaction calorimetry and drop solution calorimetry. The heat capacity curves, dominated above room temperature by the broad peak associated with the cobalt spin state transition, closely resemble those of the “simple” rare-earth cobaltites RCoO_3-δ. Similarly, trends in the enthalpies of reduction in hydrogen and the enthalpies of formation from binary oxides (R₂O₃ and CoO) are identical for (5R_0.2)CoO_3-δ and RCoO_3-δ. This indicates enhanced stability for the oxides with larger average radius of the rare-earth ions (i.e., the Goldschmidt tolerance factor closer to 1). The calculated enthalpies of mixing in the A-sublattice of (5R_0.2)CoO_3-δ are close to zero, suggesting that these solid solutions can be regarded as near-ideal ones. The absence of significant enthalpic destabilization in the (5R_0.2)CoO_3-δ oxide systems indicates the feasibility of synthesizing multiple perovskite cobaltites that are thermodynamically stable in wide temperature ranges, down to room temperature. This offers the potential to finely tune A-site ion sizes and dependent properties by varying the complex composition.

由于其独特的磁性和电子性能，基于稀土钙钛矿型钴酸盐的材料在电子和能量转换应用方面很有前景。本研究采用硝酸甘油技术合成了含有5种不同稀土元素R的a -亚晶格单相钴酸盐（5R0.2）CoO3-δ。x射线衍射（XRD）证实了（5R0.2）CoO3-δ具有正交（Pnma）钙钛矿结构，能谱分析表明这些氧化物中阳离子分布均匀。用差示扫描量热法测定了（5R0.2）CoO3-δ的热容，用还原反应量热法和滴液量热法测定了生成焓。热容曲线在室温以上以与钴自旋态转变相关的宽峰为主，与“简单”稀土钴酸盐RCoO3-δ的热容曲线非常相似。同样，在（5R0.2）CoO3-δ和RCoO3-δ中，氢的还原焓和二元氧化物（R2O3和CoO）的生成焓的变化趋势是相同的。这表明稀土离子的平均半径越大（即Goldschmidt容差系数接近1），氧化物的稳定性就越好。计算得到的（5R0.2）CoO3-δ在a -亚晶格中的混合焓接近于零，表明这些固溶体可视为接近理想的固溶体。在（5R0.2）CoO3-δ氧化物体系中没有明显的热不稳定性，这表明合成多种钙钛矿钴酸盐是可行的，这些钙钛矿钴酸盐在宽温度范围内（低至室温）都是热力学稳定的。这提供了通过改变复合成分来精细调整a位离子大小和依赖性质的潜力。

{"title":"Thermodynamics of compositionally complex (“high-entropy”) oxides – A-site mixed (5R0.2)CoO3-δ (R = rare-earth element) perovskite-type cobaltites","authors":"Vladimir V. Sereda , Dmitry S. Tsvetkov , Anna V. Sereda , Dmitry A. Malyshkin , Ivan L. Ivanov , Irina A. Bajenova , Semen S. Kuzovchikov , Alexandra V. Khvan , Andrey Yu. Zuev","doi":"10.1016/j.actamat.2026.121943","DOIUrl":"10.1016/j.actamat.2026.121943","url":null,"abstract":"<div><div>Due to their unique magnetic and electronic properties, materials based on rare-earth perovskite-type cobaltites are promising for electronic and energy conversion applications. In this study, several single-phase cobaltites (5R<sub>0.2</sub>)CoO<sub>3-δ</sub> with five different rare-earth elements R in the A-sublattice were synthesized via the glycerol-nitrate technique. X-ray diffraction (XRD) confirmed the orthorhombic (<em>Pnma</em>) perovskite structure of (5R<sub>0.2</sub>)CoO<sub>3-δ</sub>, and energy-dispersive microanalysis showed a uniform cation distribution in these oxides. The heat capacity of (5R<sub>0.2</sub>)CoO<sub>3-δ</sub> was investigated using differential scanning calorimetry, and the enthalpy of formation was determined via reduction reaction calorimetry and drop solution calorimetry. The heat capacity curves, dominated above room temperature by the broad peak associated with the cobalt spin state transition, closely resemble those of the “simple” rare-earth cobaltites RCoO<sub>3-δ</sub>. Similarly, trends in the enthalpies of reduction in hydrogen and the enthalpies of formation from binary oxides (R<sub>2</sub>O<sub>3</sub> and CoO) are identical for (5R<sub>0.2</sub>)CoO<sub>3-δ</sub> and RCoO<sub>3-δ</sub>. This indicates enhanced stability for the oxides with larger average radius of the rare-earth ions (i.e., the Goldschmidt tolerance factor closer to 1). The calculated enthalpies of mixing in the A-sublattice of (5R<sub>0.2</sub>)CoO<sub>3-δ</sub> are close to zero, suggesting that these solid solutions can be regarded as near-ideal ones. The absence of significant enthalpic destabilization in the (5R<sub>0.2</sub>)CoO<sub>3-δ</sub> oxide systems indicates the feasibility of synthesizing multiple perovskite cobaltites that are thermodynamically stable in wide temperature ranges, down to room temperature. This offers the potential to finely tune A-site ion sizes and dependent properties by varying the complex composition.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121943"},"PeriodicalIF":9.3,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995334","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

Characterization and modeling of continuous dynamic recrystallization (CDRX): Application to 2139 aluminum alloy 连续动态再结晶（CDRX）的表征与建模：在2139铝合金中的应用

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-16 DOI: 10.1016/j.actamat.2026.121922

Lahcen Abaray , Baptiste Flipon , Malik Durand , Nicolas Bayona Carrillo , Marc Bernacki

Controlling microstructure is a key factor in hot metal forming as it affects the performance of metallic materials. In high stacking-fault-energy materials, including aluminum alloys, continuous dynamic recrystallization (CDRX) drives microstructural evolution. In this study, hot compression tests were conducted on the AA2139 alloy across a wide range of thermomechanical conditions to (i) characterize the CDRX mechanism and (ii) generate experimental data for model calibration. Microstructural investigations were conducted to examine the development of grain and subgrain structures, and the evolution of disorientation distributions. Evidence of CDRX was observed through the formation of low-angle grain boundaries (LAGBs), their progressive increase in disorientation, and their transformation into high-angle grain boundaries (HAGBs), both in grain interiors and near original grain boundaries. Increasing strain promoted the progressive disorientation of LAGBs. Strain rate and temperature strongly influenced subgrain size, LAGB density, and dynamic recovery. Based on these results, a physically based CDRX model was developed by extending the work of Gourdet and Montheillet. The proposed improvements introduce the contribution of LAGB energy and disorientation angle to the subgrain-rotation law, a crystallite-size-dependent rate of LAGB creation through a refined physical description of the parameter

α

, and the incorporation of self-heating effects during deformation. Together, these developments significantly enhance the physical consistency of the model. The overall experimental trends were reproduced, including the decrease in crystallite size and the increase in LAGB density at higher strain rates and lower temperatures, as well as the higher mean LAGB disorientation angle observed at lower strain rates. In addition, the model captures the macroscopic flow stress under various thermomechanical conditions.

控制微观组织是影响金属材料性能的关键因素。在包括铝合金在内的高叠错能材料中，连续动态再结晶（CDRX）驱动着微观组织的演变。在本研究中，对AA2139合金在各种热力学条件下进行热压缩试验，以(i)表征CDRX机制，（ii）生成模型校准的实验数据。显微组织研究了晶粒和亚晶粒组织的发育以及取向失向分布的演变。在晶粒内部和原始晶界附近，低角度晶界（LAGBs）的形成、定向障碍的逐渐增加以及向高角度晶界（HAGBs）的转变，都可以观察到CDRX的证据。应变的增加促进了lagb的逐渐失向。应变速率和温度强烈影响亚晶粒尺寸、LAGB密度和动态恢复。基于这些结果，通过扩展Gourdet和Montheillet的工作，建立了一个基于物理的CDRX模型。提出的改进引入了LAGB能量和失向角对亚晶旋转规律的贡献，通过对参数α的精细物理描述，引入了LAGB产生的晶体尺寸依赖率，以及变形过程中的自热效应。总之，这些发展显著地增强了模型的物理一致性。实验重现了整体的实验趋势，包括在较高应变速率和较低温度下晶体尺寸减小和LAGB密度增加，以及在较低应变速率下观察到较高的平均LAGB失向角。此外，该模型还捕获了不同热力学条件下的宏观流变应力。

{"title":"Characterization and modeling of continuous dynamic recrystallization (CDRX): Application to 2139 aluminum alloy","authors":"Lahcen Abaray , Baptiste Flipon , Malik Durand , Nicolas Bayona Carrillo , Marc Bernacki","doi":"10.1016/j.actamat.2026.121922","DOIUrl":"10.1016/j.actamat.2026.121922","url":null,"abstract":"<div><div>Controlling microstructure is a key factor in hot metal forming as it affects the performance of metallic materials. In high stacking-fault-energy materials, including aluminum alloys, continuous dynamic recrystallization (CDRX) drives microstructural evolution. In this study, hot compression tests were conducted on the AA2139 alloy across a wide range of thermomechanical conditions to (i) characterize the CDRX mechanism and (ii) generate experimental data for model calibration. Microstructural investigations were conducted to examine the development of grain and subgrain structures, and the evolution of disorientation distributions. Evidence of CDRX was observed through the formation of low-angle grain boundaries (LAGBs), their progressive increase in disorientation, and their transformation into high-angle grain boundaries (HAGBs), both in grain interiors and near original grain boundaries. Increasing strain promoted the progressive disorientation of LAGBs. Strain rate and temperature strongly influenced subgrain size, LAGB density, and dynamic recovery. Based on these results, a physically based CDRX model was developed by extending the work of Gourdet and Montheillet. The proposed improvements introduce the contribution of LAGB energy and disorientation angle to the subgrain-rotation law, a crystallite-size-dependent rate of LAGB creation through a refined physical description of the parameter <span><math><mi>α</mi></math></span>, and the incorporation of self-heating effects during deformation. Together, these developments significantly enhance the physical consistency of the model. The overall experimental trends were reproduced, including the decrease in crystallite size and the increase in LAGB density at higher strain rates and lower temperatures, as well as the higher mean LAGB disorientation angle observed at lower strain rates. In addition, the model captures the macroscopic flow stress under various thermomechanical conditions.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121922"},"PeriodicalIF":9.3,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995333","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

Multi-objective topology optimization of Ni–YSZ anode microstructure in anode-supported solid oxide fuel cells and performance analysis of cell 阳极支撑固体氧化物燃料电池Ni-YSZ阳极微观结构多目标拓扑优化及电池性能分析

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-15 DOI: 10.1016/j.actamat.2026.121942

Yufeng Du , Lei Fu , Bingyao Yi , Dingxi Xue , Yang Wan , Guojun Li

Solid oxide fuel cells (SOFCs) experience excessive thermal stress and microcrack formation at high operating temperatures, which severely limits power output and service life. To address this, we develop a multi-objective topology optimization framework for Ni-YSZ anode microstructures. Eight objective-function weight combinations (ω_CET, ω_th, ω_error) and four three-phase material volume ratios are systematically examined. The optimized configurations consistently form cruciform YSZ skeletons with centrally symmetric Ni embedding. On average, these designs achieve a 30% reduction in elastic modulus, a 20% decrease in the coefficient of thermal expansion (CET), and a 70% increase in thermal conductivity. For microstructures optimized under AOF8, the triple-phase boundary (TPB) density increases by 5–8 times relative to conventional, non-optimized anodes. Single-cell simulations confirm that these microstructural improvements translate into an increase in current density of approximately 0.4 A·cm⁻² and an enhancement in maximum power density of about 1.5 W·cm⁻². Notably, AOF2, which prioritizes thermal conductivity, effectively reduces thermal stress concentration, whereas AOF8, which prioritizes TPB density, yields markedly enhanced electrochemical activity. An inverse association between gains in thermal conductivity and TPB density indicates inherent trade-offs among key material properties. This study establishes clear microstructure–property relationships that enable concurrent optimization of thermal stability and electrochemical performance. The proposed framework provides practical design guidance for next-generation SOFC anodes, with AOF7, characterized by the lowest elastic modulus, and AOF8, characterized by the highest TPB density, offering targeted solutions for severe thermal cycling and high-power applications, respectively.

固体氧化物燃料电池（sofc）在高温下会产生过大的热应力和微裂纹，严重限制了功率输出和使用寿命。为了解决这个问题，我们开发了一个Ni-YSZ阳极微结构的多目标拓扑优化框架。系统考察了8种目标函数权重组合（ωCET, ωth, ωerror）和4种三相材料体积比。优化后的结构一致形成中心对称镍嵌入的十字形YSZ骨架。平均而言，这些设计可使弹性模量降低30%，热膨胀系数（CET）降低20%，导热系数提高70%。对于在AOF8下优化的微观结构，三相边界（TPB）密度相对于传统的、未优化的阳极提高了5-8倍。单电池模拟证实，这些微观结构的改进转化为电流密度增加了约0.4 A·cm - 2，最大功率密度提高了约1.5 W·cm - 2。值得注意的是，优先考虑导热系数的AOF2可以有效降低热应力集中，而优先考虑TPB密度的AOF8可以显著增强电化学活性。导热系数增益与TPB密度之间的负相关关系表明了关键材料性能之间的内在权衡。本研究建立了清晰的微结构-性能关系，使热稳定性和电化学性能同时优化成为可能。该框架为下一代SOFC阳极提供了实用的设计指导，其中具有最低弹性模量的AOF7和具有最高TPB密度的AOF8分别为剧烈热循环和高功率应用提供了有针对性的解决方案。

{"title":"Multi-objective topology optimization of Ni–YSZ anode microstructure in anode-supported solid oxide fuel cells and performance analysis of cell","authors":"Yufeng Du , Lei Fu , Bingyao Yi , Dingxi Xue , Yang Wan , Guojun Li","doi":"10.1016/j.actamat.2026.121942","DOIUrl":"10.1016/j.actamat.2026.121942","url":null,"abstract":"<div><div>Solid oxide fuel cells (SOFCs) experience excessive thermal stress and microcrack formation at high operating temperatures, which severely limits power output and service life. To address this, we develop a multi-objective topology optimization framework for Ni-YSZ anode microstructures. Eight objective-function weight combinations (<em>ω</em><sub>CET</sub>, <em>ω</em><sub>th</sub>, <em>ω</em><sub>error</sub>) and four three-phase material volume ratios are systematically examined. The optimized configurations consistently form cruciform YSZ skeletons with centrally symmetric Ni embedding. On average, these designs achieve a 30% reduction in elastic modulus, a 20% decrease in the coefficient of thermal expansion (CET), and a 70% increase in thermal conductivity. For microstructures optimized under AOF8, the triple-phase boundary (TPB) density increases by 5–8 times relative to conventional, non-optimized anodes. Single-cell simulations confirm that these microstructural improvements translate into an increase in current density of approximately 0.4 A·cm<sup>−2</sup> and an enhancement in maximum power density of about 1.5 W·cm<sup>−2</sup>. Notably, AOF2, which prioritizes thermal conductivity, effectively reduces thermal stress concentration, whereas AOF8, which prioritizes TPB density, yields markedly enhanced electrochemical activity. An inverse association between gains in thermal conductivity and TPB density indicates inherent trade-offs among key material properties. This study establishes clear microstructure–property relationships that enable concurrent optimization of thermal stability and electrochemical performance. The proposed framework provides practical design guidance for next-generation SOFC anodes, with AOF7, characterized by the lowest elastic modulus, and AOF8, characterized by the highest TPB density, offering targeted solutions for severe thermal cycling and high-power applications, respectively.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121942"},"PeriodicalIF":9.3,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145972493","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

Outstanding strength–ductility synergy in a gradient stainless steel produced by additive manufacturing 通过增材制造生产的梯度不锈钢的杰出强度-延性协同作用

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-15 DOI: 10.1016/j.actamat.2026.121940

Shaohua Yan , Ilchat Sabirov , Qinghua Qin , Xiaozhou Liao

Additively manufactured (AM) 316 L stainless steel exhibits only moderate room-temperature strength, limiting its use in demanding service. Ceramic reinforcement can raise strength but typically degrades ductility. Here, we employ multi-material AM to architect gradient structures comprising 316 L and 316L/TiC. The as-built alloys display four coupled gradients, including grain size, grain-boundary character, precipitate distribution, and chemical composition, at a complexity not achieved by traditional synthesis approaches. These gradient structures deliver concurrent increases in yield and ultimate tensile strengths with only marginal loss of ductility; their strength–ductility combinations surpass those of both homogeneous and conventionally gradient 316 L produced by AM or traditional synthesis approaches. Mechanistically, the superior performance arises from refined grains, high densities of nanoscale precipitates and twin boundaries, and the associated elevated strain-hardening capacity that stabilizes uniform plastic flow. We further develop a quantitative strength model that superposes contributions from grain refinement, precipitation, twinning, and compositional gradients, accurately predicting the measured yield strengths. These findings establish a pathway for designing gradient metal alloys with exceptional mechanical properties via multi-material AM.

增材制造（AM） 316L不锈钢仅表现出中等的室温强度，限制了其在苛刻服务中的使用。陶瓷增强可以提高强度，但通常会降低延展性。在这里，我们采用多材料AM来构建由316L和316L/TiC组成的梯度结构。合成的合金显示出四个耦合梯度，包括晶粒尺寸、晶界特征、析出相分布和化学成分，其复杂性是传统合成方法无法实现的。这些梯度结构可以同时提高屈服强度和极限抗拉强度，而延性只有轻微的损失；它们的强度-延性组合超过了由AM或传统合成方法生产的均质和常规梯度316L。在力学上，优异的性能来自于细化的晶粒、高密度的纳米级析出物和孪晶界，以及相关的应变硬化能力的提高，从而稳定了均匀的塑性流动。我们进一步开发了一个定量强度模型，该模型叠加了晶粒细化、沉淀、孪生和成分梯度的贡献，准确地预测了测量的屈服强度。这些发现为利用多材料增材制造技术设计具有优异力学性能的梯度金属合金开辟了一条途径。

{"title":"Outstanding strength–ductility synergy in a gradient stainless steel produced by additive manufacturing","authors":"Shaohua Yan , Ilchat Sabirov , Qinghua Qin , Xiaozhou Liao","doi":"10.1016/j.actamat.2026.121940","DOIUrl":"10.1016/j.actamat.2026.121940","url":null,"abstract":"<div><div>Additively manufactured (AM) 316 L stainless steel exhibits only moderate room-temperature strength, limiting its use in demanding service. Ceramic reinforcement can raise strength but typically degrades ductility. Here, we employ multi-material AM to architect gradient structures comprising 316 L and 316L/TiC. The as-built alloys display four coupled gradients, including grain size, grain-boundary character, precipitate distribution, and chemical composition, at a complexity not achieved by traditional synthesis approaches. These gradient structures deliver concurrent increases in yield and ultimate tensile strengths with only marginal loss of ductility; their strength–ductility combinations surpass those of both homogeneous and conventionally gradient 316 L produced by AM or traditional synthesis approaches. Mechanistically, the superior performance arises from refined grains, high densities of nanoscale precipitates and twin boundaries, and the associated elevated strain-hardening capacity that stabilizes uniform plastic flow. We further develop a quantitative strength model that superposes contributions from grain refinement, precipitation, twinning, and compositional gradients, accurately predicting the measured yield strengths. These findings establish a pathway for designing gradient metal alloys with exceptional mechanical properties via multi-material AM.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121940"},"PeriodicalIF":9.3,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145972496","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

“Charge pump-ion pump” coupling in moss-like CoNiFeMnZn-LDH/Ni heterostructures for efficient electrocatalytic water splitting 苔藓状CoNiFeMnZn-LDH/Ni异质结构中的“电荷泵-离子泵”耦合用于高效电催化水分解

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-15 DOI: 10.1016/j.actamat.2026.121934

Cheng Gong , Weixin Li , Xuan He , Xing Du , Daheng Wang , Hui Chen , Wei Fang , Haijun Zhang , Lei Zhao , Yang Chai

Electrocatalytic efficiency is fundamentally governed by reaction kinetics and electron transfer behavior. Herein, we propose a novel dual-field coupling strategy that integrates built-in electric fields (BEF) and localized electric fields (LEF) to establish “charge pump-ion pump” synergistic mechanisms, overcoming the kinetic limitations of alkaline water splitting. The moss-like CoNiFeMnZn-LDH/Ni features an open-porous structure with abundant high-curvature surfaces and pronounced electronegativity differences among its constituent elements. This unique structural configuration induces LEF concentration at the tip, thereby enhancing the adsorption kinetics of H⁺/OH⁻ ions. The coupling of CoNiFeMnZn-LDH and Ni nanoparticles (NPs) forms Mott-Schottky heterojunctions, generating a BEF that regulates the d-band center and optimizes interfacial charge distribution to boost electrochemical performance. The Mott-Schottky-derived BEF acts as a charge pump, not only amplifying the strength of the LEF but also, in turn, having its interfacial charge-separation efficiency enhanced and optimized by the amplified LEF. The characterization and theoretical calculations demonstrate the enhanced electrocatalytic activity and rapid reaction kinetics benefiting from the dual-field coupling synergistic effect. The optimized CoNiFeMnZn-LDH/Ni delivers a low overpotentials of 215 mV at 10 mA cm⁻² (98 mV at 10 mA cm⁻²) in 1.0 M KOH towards the OER (HER). This study proposes a tunable strategy to synergistic modulate reaction kinetics and electron transfer behavior for overall water splitting.

电催化效率从根本上是由反应动力学和电子转移行为决定的。在此，我们提出了一种新的双场耦合策略，将内置电场（BEF）和局部电场（LEF）集成在一起，建立“电荷泵-离子泵”协同机制，克服了碱性水分裂的动力学限制。类似苔藓的CoNiFeMnZn-LDH/Ni具有开放多孔结构，具有丰富的高曲率表面，其组成元素之间存在明显的电负性差异。这种独特的结构配置诱导了尖端的LEF浓度，从而增强了H+/OH−离子的吸附动力学。CoNiFeMnZn-LDH和Ni纳米颗粒（NPs）的耦合形成Mott-Schottky异质结，产生BEF，调节d波段中心并优化界面电荷分布，从而提高电化学性能。mott - schottkey衍生的BEF作为电荷泵，不仅放大了LEF的强度，而且通过放大的LEF增强和优化了其界面电荷分离效率。表征和理论计算表明，双场耦合协同效应增强了电催化活性，加快了反应动力学。优化后的CoNiFeMnZn-LDH/Ni在1.0 M KOH条件下，在10 mA cm−2条件下具有215 mV （10 mA cm−2条件下为98 mV）的低过电位。本研究提出了一个可调策略，以协同调节反应动力学和电子转移行为的整体水分解。

{"title":"“Charge pump-ion pump” coupling in moss-like CoNiFeMnZn-LDH/Ni heterostructures for efficient electrocatalytic water splitting","authors":"Cheng Gong , Weixin Li , Xuan He , Xing Du , Daheng Wang , Hui Chen , Wei Fang , Haijun Zhang , Lei Zhao , Yang Chai","doi":"10.1016/j.actamat.2026.121934","DOIUrl":"10.1016/j.actamat.2026.121934","url":null,"abstract":"<div><div>Electrocatalytic efficiency is fundamentally governed by reaction kinetics and electron transfer behavior. Herein, we propose a novel dual-field coupling strategy that integrates built-in electric fields (BEF) and localized electric fields (LEF) to establish “charge pump-ion pump” synergistic mechanisms, overcoming the kinetic limitations of alkaline water splitting. The moss-like CoNiFeMnZn-LDH/Ni features an open-porous structure with abundant high-curvature surfaces and pronounced electronegativity differences among its constituent elements. This unique structural configuration induces LEF concentration at the tip, thereby enhancing the adsorption kinetics of H<sup>+</sup>/OH<sup>−</sup> ions. The coupling of CoNiFeMnZn-LDH and Ni nanoparticles (NPs) forms Mott-Schottky heterojunctions, generating a BEF that regulates the <span>d</span>-band center and optimizes interfacial charge distribution to boost electrochemical performance. The Mott-Schottky-derived BEF acts as a charge pump, not only amplifying the strength of the LEF but also, in turn, having its interfacial charge-separation efficiency enhanced and optimized by the amplified LEF. The characterization and theoretical calculations demonstrate the enhanced electrocatalytic activity and rapid reaction kinetics benefiting from the dual-field coupling synergistic effect. The optimized CoNiFeMnZn-LDH/Ni delivers a low overpotentials of 215 mV at 10 mA cm<sup>−2</sup> (98 mV at 10 mA cm<sup>−2</sup>) in 1.0 M KOH towards the OER (HER). This study proposes a tunable strategy to synergistic modulate reaction kinetics and electron transfer behavior for overall water splitting.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121934"},"PeriodicalIF":9.3,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035051","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

Synergistic enhancement of strength-ductility in a refractory multi-principal element alloy via multimodal regulation of multiscale barriers 通过多尺度障碍的多模态调节协同增强难熔多主元素合金的强度-延性

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-15 DOI: 10.1016/j.actamat.2026.121941

Yaxi Ma , Luyan Yang , Yixi Hou , Honghong Su , Xiaoran Zhao , Cheng Jiang , Ze Zhang , Shengcheng Mao , Xiaodong Han

Refractory multi-principal element alloys (RMPEAs) are promising structural materials for aerospace and nuclear applications due to their exceptional mechanical properties. However, these alloys face two critical challenges: intrinsic room-temperature brittleness caused by restricted dislocation mobility and limited strain hardening capacity resulting from planar slip-dominated deformation. This study proposes a novel thermomechanical processing route termed CRLAPA (cold rolling followed by low-temperature aging and partial annealing) to construct multiscale heterostructures in a Ti₃₃Zr₃₃Nb₂₀Al₉V₅ RMPEA, thereby achieving a high tensile yield strength of 1323 MPa with 19 % fracture elongation. The bimodal grain structure, engineered via recrystallization driven by dislocation density gradients, facilitates complementary deformation modes: ultrafine grains effectively store geometrically necessary dislocations (GNDs) for rapid hardening, whereas fine grains accommodate statistically stored dislocations (SSDs) to sustain plastic flow. The B2-type short-range order (SRO) in conjunction with enhanced local lattice distortion, promotes the formation of slip bands by effectively pinning dislocation motion and thereby facilitating dislocation multiplication. These slip bands interact with microbands to form stress redistribution pathways, thereby delaying strain localization and maintaining sustained work hardening. This work establishes a viable strategy for overcoming the strength-ductility trade-off in RMPEAs by multimodal regulation of multiscale barriers.

耐火多主元素合金（rmpea）由于其优异的力学性能，在航空航天和核结构材料中具有广阔的应用前景。然而，这些合金面临两个关键挑战：位错迁移率受限导致的固有室温脆性和平面滑移主导变形导致的有限应变硬化能力。本研究提出了一种新的热处理工艺——CRLAPA（冷轧+低温时效+部分退火），在Ti33Zr33Nb20Al9V5 RMPEA中构建多尺度异质组织，从而获得了1323 MPa的高抗拉屈服强度和19%的断裂伸长率。由位错密度梯度驱动的再结晶形成的双峰晶粒结构促进了互补的变形模式：超细晶粒有效地存储几何上必要的位错（GNDs）以实现快速硬化，而细晶粒容纳统计上存储的位错（ssd）以维持塑性流动。b2型短程有序（SRO）与增强的局部晶格畸变一起，通过有效地固定位错运动，从而促进位错增殖，从而促进滑移带的形成。这些滑动带与微带相互作用形成应力重新分配途径，从而延迟应变局部化并维持持续的加工硬化。本研究建立了一种可行的策略，通过多尺度障碍的多模式调节来克服rmpea中的强度-延性权衡。

{"title":"Synergistic enhancement of strength-ductility in a refractory multi-principal element alloy via multimodal regulation of multiscale barriers","authors":"Yaxi Ma , Luyan Yang , Yixi Hou , Honghong Su , Xiaoran Zhao , Cheng Jiang , Ze Zhang , Shengcheng Mao , Xiaodong Han","doi":"10.1016/j.actamat.2026.121941","DOIUrl":"10.1016/j.actamat.2026.121941","url":null,"abstract":"<div><div>Refractory multi-principal element alloys (RMPEAs) are promising structural materials for aerospace and nuclear applications due to their exceptional mechanical properties. However, these alloys face two critical challenges: intrinsic room-temperature brittleness caused by restricted dislocation mobility and limited strain hardening capacity resulting from planar slip-dominated deformation. This study proposes a novel thermomechanical processing route termed CRLAPA (cold rolling followed by low-temperature aging and partial annealing) to construct multiscale heterostructures in a Ti<sub>33</sub>Zr<sub>33</sub>Nb<sub>20</sub>Al<sub>9</sub>V<sub>5</sub> RMPEA, thereby achieving a high tensile yield strength of 1323 MPa with 19 % fracture elongation. The bimodal grain structure, engineered via recrystallization driven by dislocation density gradients, facilitates complementary deformation modes: ultrafine grains effectively store geometrically necessary dislocations (GNDs) for rapid hardening, whereas fine grains accommodate statistically stored dislocations (SSDs) to sustain plastic flow. The B2-type short-range order (SRO) in conjunction with enhanced local lattice distortion, promotes the formation of slip bands by effectively pinning dislocation motion and thereby facilitating dislocation multiplication. These slip bands interact with microbands to form stress redistribution pathways, thereby delaying strain localization and maintaining sustained work hardening. This work establishes a viable strategy for overcoming the strength-ductility trade-off in RMPEAs by multimodal regulation of multiscale barriers.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121941"},"PeriodicalIF":9.3,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145993368","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

Irradiation response during the early stages of alpha radiation damage in mesoporous nanocrystalline ceria films 介孔氧化铈纳米晶膜α辐射损伤早期的辐照响应

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-15 DOI: 10.1016/j.actamat.2026.121944

Jean-Marc Costantini , Aurélien Canizares , Patrick Simon , Christel Laberty-Robert , Gérald Lelong , Maxime Guillaumet , Nathalie Moncoffre , Gianguido Baldinozzi

We have studied the effect of alpha radiation on mesoporous ceria in the very early stages of damage by electronic energy loss processes. Most of the studies of the radiation effects in nanocrystalline ceria were performed on relatively dense samples and in the ballistic regime of binary collisions. Few studies on ceramic systems have focused on radiation effects in loosely packed nanocrystalline systems with predominantly free surfaces. Free surfaces are believed to be critical for radiation resistance, but few studies specifically investigated radiation-induced changes of structural correlations in such systems. We irradiated mesoporous nanocrystalline CeO₂ films with well-characterized architectures with 800 keV He⁺ ions. Glancing incidence X-ray diffraction (GIXRD), Raman spectroscopy, and diffuse reflectance spectroscopy were used to measure the quantitative changes in structural correlations and the modification of electronic properties as a function of ion fluence. We show that the decrease of phonon lifetimes and the changes of the optical spectra depends on the excess polaron concentration produced by the irradiation. The implications of these findings for the properties and the radiation resistance of these systems are discussed.

我们研究了α辐射对介孔氧化铈在电子能量损失过程损伤的早期阶段的影响。大多数关于纳米晶二氧化铈辐射效应的研究都是在相对致密的样品和二元碰撞的弹道状态下进行的。很少有关于陶瓷系统的研究集中在以自由表面为主的松散堆积纳米晶系统中的辐射效应。自由表面被认为是抗辐射的关键，但很少有研究专门研究辐射引起的结构相关性的变化。我们用800 keV He+离子辐照具有良好结构的介孔纳米晶CeO2薄膜。利用掠射x射线衍射（GIXRD）、拉曼光谱和漫反射光谱测量了结构相关性的定量变化和电子性质随离子影响的变化。我们发现声子寿命的减少和光谱的变化与辐照产生的过量极化子浓度有关。讨论了这些发现对这些体系的性能和抗辐射性能的影响。

{"title":"Irradiation response during the early stages of alpha radiation damage in mesoporous nanocrystalline ceria films","authors":"Jean-Marc Costantini , Aurélien Canizares , Patrick Simon , Christel Laberty-Robert , Gérald Lelong , Maxime Guillaumet , Nathalie Moncoffre , Gianguido Baldinozzi","doi":"10.1016/j.actamat.2026.121944","DOIUrl":"10.1016/j.actamat.2026.121944","url":null,"abstract":"<div><div>We have studied the effect of alpha radiation on mesoporous ceria in the very early stages of damage by electronic energy loss processes. Most of the studies of the radiation effects in nanocrystalline ceria were performed on relatively dense samples and in the ballistic regime of binary collisions. Few studies on ceramic systems have focused on radiation effects in loosely packed nanocrystalline systems with predominantly free surfaces. Free surfaces are believed to be critical for radiation resistance, but few studies specifically investigated radiation-induced changes of structural correlations in such systems. We irradiated mesoporous nanocrystalline CeO<sub>2</sub> films with well-characterized architectures with 800 keV He<sup>+</sup> ions. Glancing incidence X-ray diffraction (GIXRD), Raman spectroscopy, and diffuse reflectance spectroscopy were used to measure the quantitative changes in structural correlations and the modification of electronic properties as a function of ion fluence. We show that the decrease of phonon lifetimes and the changes of the optical spectra depends on the excess polaron concentration produced by the irradiation. The implications of these findings for the properties and the radiation resistance of these systems are discussed.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121944"},"PeriodicalIF":9.3,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145972495","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

Grain size effect on segregation kinetics of B and Mo at the austenite grain boundary in Mo-B combined addition steel 晶粒尺寸对Mo-B复合添加钢中B和Mo在奥氏体晶界的偏析动力学的影响

IF 9.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-15 DOI: 10.1016/j.actamat.2026.121939

Jun Takahashi , Kazuto Kawakami , Daiki Terazawa , Kyohhei Ishikawa

To effectively use boron (B) as a hardenability element in steel, it is necessary to understand the segregation kinetics of B at austenite grain boundaries (GBs). This study revealed for the first time by experiment that the grain diameter has a significant effect on the behavior of B segregation, even with the normal grain size of practical steels. Using different grain diameter specimens of steel containing 5 massppm B and 0.5mass% molybdenum (Mo), the cooling rate dependence of B and Mo amounts segregated at prior austenite GBs was investigated by atom probe tomography analysis. With decreasing cooling rate from the austenitizing temperature of 950 °C, the amount of B segregation approached a maximum value at high cooling rates for the small-grain specimen and at low cooling rates for the large-grain specimen. The maximum value for the large-grain specimen was more than twice that of the small-grain specimen. The characteristic behaviors were explained quantitatively using a diffusion-limited equilibrium segregation model that considered the grain diameter. In contrast, the amount of Mo segregation continued to increase with decreasing cooling rate, and the large-grain specimen exhibited slightly larger segregation amounts at lower cooling rates. The origin of the grain size effect on austenite GB segregation was primarily the difference in the thermal equilibrium value for B and the co-segregation of Mo with B. This grain size effect also affects the hardenability through the segregation behavior

为了有效地利用硼作为钢中的淬透性元素，有必要了解硼在奥氏体晶界处的偏析动力学。本研究首次通过实验揭示了晶粒直径对B偏析行为的显著影响，即使是在实际钢的正常晶粒尺寸下也是如此。采用原子探针层析成像分析方法，研究了不同晶粒直径的含钼量为0.5质量%、含B量为5质量pm的钢试样，在先前的奥氏体GBs中分离的B和Mo量对冷却速率的依赖关系。从950℃奥氏体化温度开始，随着冷却速率的降低，小晶粒试样在高冷却速率下的B偏析量达到最大值，而大晶粒试样在低冷却速率下的B偏析量达到最大值。大晶粒试样的最大值是小晶粒试样的两倍以上。使用考虑晶粒直径的扩散限制平衡偏析模型定量解释了这些特征行为。相反，Mo偏析量随着冷却速率的降低而增加，大晶粒试样在较低冷却速率下偏析量略大。晶粒尺寸对奥氏体GB偏析的影响主要来源于B的热平衡值和Mo与B的共偏析的差异，晶粒尺寸效应还通过偏析行为影响淬透性

{"title":"Grain size effect on segregation kinetics of B and Mo at the austenite grain boundary in Mo-B combined addition steel","authors":"Jun Takahashi , Kazuto Kawakami , Daiki Terazawa , Kyohhei Ishikawa","doi":"10.1016/j.actamat.2026.121939","DOIUrl":"10.1016/j.actamat.2026.121939","url":null,"abstract":"<div><div>To effectively use boron (B) as a hardenability element in steel, it is necessary to understand the segregation kinetics of B at austenite grain boundaries (GBs). This study revealed for the first time by experiment that the grain diameter has a significant effect on the behavior of B segregation, even with the normal grain size of practical steels. Using different grain diameter specimens of steel containing 5 massppm B and 0.5mass% molybdenum (Mo), the cooling rate dependence of B and Mo amounts segregated at prior austenite GBs was investigated by atom probe tomography analysis. With decreasing cooling rate from the austenitizing temperature of 950 °C, the amount of B segregation approached a maximum value at high cooling rates for the small-grain specimen and at low cooling rates for the large-grain specimen. The maximum value for the large-grain specimen was more than twice that of the small-grain specimen. The characteristic behaviors were explained quantitatively using a diffusion-limited equilibrium segregation model that considered the grain diameter. In contrast, the amount of Mo segregation continued to increase with decreasing cooling rate, and the large-grain specimen exhibited slightly larger segregation amounts at lower cooling rates. The origin of the grain size effect on austenite GB segregation was primarily the difference in the thermal equilibrium value for B and the co-segregation of Mo with B. This grain size effect also affects the hardenability through the segregation behavior</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121939"},"PeriodicalIF":9.3,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145972494","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