Acta Materialia最新文献_第7页

Electronic band structure engineering in ALD HfO2: Linking impurity chemistry to electronic performance and charge transport ALD HfO2的电子能带结构工程：将杂质化学与电子性能和电荷输运联系起来

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

Acta Materialia

Pub Date : 2025-11-29 DOI: 10.1016/j.actamat.2025.121780

Bingbing Xia , Guocong Lin , Jean-Jacques Ganem , Emrick Briand , Sebastien Steydli , Jurgen von Bardeleben , Ian. Vickridge , Aleksandra Baron-Wiechec

This work resolves fundamental knowledge gaps in high-k dielectric engineering by establishing the first direct causal links between atomic-layer deposition (ALD) conditions, defect speciation, and electronic structure evolution in HfO₂ thin films. Through an innovative multimodal methodology combining ion beam analysis (IBA), XPS, UPS, LEIPS, and spectroscopic defect analysis, we demonstrate temperature-controlled transformation of band alignment. At low temperatures, hydroxyl‑related species stabilize passivating dipoles that preserve favorable band alignment, while higher temperatures promote carbon incorporation and oxygen-related defects that degrade dielectric reliability. Crucially, we provide the first quantitative measurement of conduction band minimum (CBM) reduction and direct experimental evidence linking unoccupied state modifications to specific defect configurations via LEIPS-EPR correlation, addressing the correlation between specific defect configurations and unoccupied state modulation in ALD HfO₂ and a major gap in understanding defect-driven electronic structure tuning.

These insights not only advance fundamental understanding of defect–electronic structure relationships in HfO₂ but also offer practical guidelines for tailoring ALD processes in applications ranging from resistive memory to CMOS gate dielectrics.

这项工作通过建立HfO2薄膜中原子层沉积（ALD）条件、缺陷形成和电子结构演变之间的直接因果关系，解决了高k介电工程中的基础知识空白。通过结合离子束分析（IBA）、XPS、UPS、LEIPS和光谱缺陷分析的创新多模态方法，我们展示了带对准的温控转变。在低温下，羟基相关物质稳定钝化偶极子，保持良好的能带排列，而高温促进碳掺入和氧相关缺陷，降低电介质的可靠性。至关重要的是，我们提供了第一个导带最小值（CBM）减少的定量测量和通过LEIPS-EPR相关性将未占据态修改与特定缺陷构型联系起来的直接实验证据，解决了ALD HfO2中特定缺陷构型与未占据态调制之间的相关性，并在理解缺陷驱动的电子结构调谐方面存在重大差距。这些见解不仅促进了对HfO2中缺陷电子结构关系的基本理解，而且还为从电阻存储器到CMOS栅极电介质等应用中定制ALD工艺提供了实用指南。

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引用次数: 0

A dual-phase Ti-6.5Al-2V-2Mo-1Nb-14Zr-0.1Si alloy with superior 600 °C strength and ductility developed from Ti-6Al-4V cluster formula 由Ti-6Al-4V晶簇配方发展而成的双相Ti-6.5Al-2V-2Mo-1Nb-14Zr-0.1Si合金，具有优异的600°C强度和延展性

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

Acta Materialia

Pub Date : 2025-11-29 DOI: 10.1016/j.actamat.2025.121782

Mengfan Song , Cenyang Wang , Chuisen Kong , Qing Wang , Chuang Dong

Dual-phase Ti alloys, recognized for excellent mechanical properties and processability, cannot withstand service temperatures above 500 °C. In this paper, a dual-phase alloy Ti-6.5Al-2V-2Mo-1Nb-14Zr-0.1Si (DT600) is developed, whose high-temperature performance is comparable to those of prevailing near-α 600 °C Ti alloys. The composition design follows the composition formula {Al₂Ti₁₄}₁₂+β-{Al₁V₂Ti₁₅}₅ of popular dual-phase Ti-6Al-4V, via enhanced Al, partial replacement of V by stronger β stabilizers Mo and Nb, and additional silicide formers Zr and Si, into α-{(Al,Si)₂(Ti,Zr)₁₄}₁₂+β-{Al₂(Mo,Nb,V)₂(Ti,Zr)₁₄}₅. 80 g ingots of DT600 and Ti-6Al-4V were prepared by arc melting and copper mold casting, followed by annealing at 700 °C for 2 h. Due to fine silicide precipitation (∼50 nm) and basket-weave α lamellar (∼260 nm) microstructure, its tensile properties at room temperature (R_m = 1321 MPa, R_p0.2 = 1242 MPa, and A = 5.2%) are superior to the reference Ti-6Al-4 V alloy (1004 MPa, 855 MPa, and 6.1%). Most importantly, this alloy achieves an unprecedented level of 600 °C tensile performance (739 MPa, 623 MPa, 46.2%), approaching the strength level of prevailing high-temperature near-α IMI834 grade, with much enhanced plasticity. The microstructure mechanism behind such superb performance is fully discussed. The development of DT600 demonstrates the usefulness of the cluster formula approach in accurate composition design of high-temperature Ti alloys.

双相钛合金具有优异的机械性能和加工性能，但不能承受500°C以上的使用温度。本文制备了Ti-6.5 al- 2v - 2mo - 1nb - 14zr -0.1 si （DT600）双相合金，其高温性能可与目前流行的近α 600℃Ti合金相媲美。组成设计遵循流行的双相Ti- 6al - 4v的组成公式{Al2Ti14}12+β-{Al1V2Ti15}5，通过增强Al，用更强的β稳定剂Mo和Nb部分取代V，以及添加硅化物形成物Zr和Si，形成α-{(Al,Si)2(Ti,Zr)14}12+β-{Al2(Mo,Nb，V)2(Ti,Zr)14}5。采用电弧熔炼和铜模铸造法制备了80g DT600和Ti-6Al-4V铸锭，然后在700℃下退火2小时。由于细硅化物析出（~ 50 nm）和篮织α片层（~ 260 nm）组织，其室温拉伸性能（Rm = 1321 MPa, Rp0.2 = 1242 MPa, A = 5.2%）优于参考Ti-6Al-4V合金（1004 MPa， 855 MPa和6.1%）。最重要的是，该合金达到了前所未有的600°C拉伸性能（739 MPa, 623 MPa, 46.2%），接近流行的高温近α IMI834等级的强度水平，塑性大大提高。充分讨论了这种优异性能背后的微观结构机制。DT600的发展证明了簇式方法在高温钛合金精确成分设计中的实用性。

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引用次数: 0

The thermal and mechanical response of refractory alloys at ultrahigh temperatures 高温下难熔合金的热力学响应

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

Acta Materialia

Pub Date : 2025-11-29 DOI: 10.1016/j.actamat.2025.121781

Syed I.A. Jalali , Michael Patullo , Sharon Park , Carolina Frey , Kaitlyn M. Mullin , Leah H. Mills , Velat Kilic , Colin Goodman , Mark Foster , Tresa M. Pollock , Kevin J. Hemker

A novel ultrahigh temperature load frame has been developed to characterize material properties at temperatures as high as 3410 °C. This study highlights advancements in the integration of ultraviolet imaging and digital image correlation up to 2000 °C with multispectral pyrometry and the ultrahigh temperature load frame. This integrated microscopy and pyrometry for advanced characterization of thermal and mechanical properties approach enables precise and temperature-dependent measurement of strain, elastic modulus, and the coefficient of thermal expansion, as well as solidus and liquidus temperatures. Moreover, the ability to measure emissivity and temperature with high accuracy provides critical insights into the thermal behavior of refractory alloys. By applying these tools to ATI C103^TM and various refractory multi-principal element alloys, we demonstrate the ability to successfully characterize melting transitions and thermoelastic strains, as well as creating robust temperature-dependent datasets that accelerates component design and the integration of ultrahigh temperature materials.

一种新型的超高温负载框架已经开发出来，以表征材料在高达3410°C的温度下的性能。这项研究强调了在高达2000°C的紫外成像和数字图像相关集成方面的进步，多光谱高温法和超高温负载框架。这种集成的显微镜和高温法用于高级表征热学和机械性能的方法，可以精确地测量应变、弹性模量、热膨胀系数以及固相和液相温度。此外，高精度测量发射率和温度的能力为耐火合金的热行为提供了重要的见解。通过将这些工具应用于ATI C103TM和各种难熔多主元素合金，我们展示了：成功表征熔融转变和热弹性应变的能力，为增强超高温材料的开发和集成创建强大的温度相关数据集。

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引用次数: 0

Electrically charged dislocations in ionic ceramics 离子陶瓷中的带电位错

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

Acta Materialia

Pub Date : 2025-11-28 DOI: 10.1016/j.actamat.2025.121778

K.S.N. Vikrant , R. Edwin García

A thermodynamically consistent phase field theory describing coupled electrical, chemical, and mechanical effects on charged dislocations in ionic ceramics is presented. The formulation results in a generalized multiphysical Peach–Köhler force, establishing a critical electro-chemo-mechanical force necessary for dislocation motion, proportional to solute and point defect segregation. For static dislocations in 3% Yttria Stabilized Zirconia (3YSZ), a multipolar electrostatic field develops near the dislocation core, enhancing conductivity along the line. For moving dislocations, three regimes are identified: (1) the small velocity regime, where solute and charge lock the linear defect in place; (2) the intermediate velocity regime, where the electrochemomechanical field stretches ahead of the moving dislocation due to ionic charge shedding; and (3) the high velocity regime, where the dislocation escapes the solute-induced drag forces, enabling large plastic deformation. Conditions for the Portevin–Le Chatelier effect to take place, in agreement with literature accounts, are identified. The resultant temperature-dependent, solute and charge segregation and its effects on sintering are discussed in the context of Joule heating, reduction of local critical stress for densification, and promotion of macroscopic thermal and plastic runaway.

提出了一种描述离子陶瓷中带电位错的电、化学和力学耦合效应的热力学一致相场理论。该公式得出了广义的多物理Peach-Köhler力，建立了位错运动所需的临界电化学-机械力，与溶质和点缺陷偏析成正比。对于3%钇稳定氧化锆（3YSZ）中的静电位错，在位错核心附近形成多极静电场，增强了沿线的电导率。对于移动位错，确定了三种状态：(1)小速度状态，其中溶质和电荷将线性缺陷锁定在原位；(2)中间速度区，由于离子电荷脱落，电化学电场在移动位错之前伸展；(3)高速区，位错摆脱了溶质诱导的阻力，实现了大的塑性变形。波特文-勒夏特列效应发生的条件与文献记载一致。由此产生的温度依赖，溶质和电荷偏析及其对烧结的影响，在焦耳加热，降低局部临界应力和促进宏观热塑性失控（闪变事件）的背景下进行了讨论。

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引用次数: 0

Diffusivity and solubility of tritium in amorphous silica: A computational study 氚在无定形二氧化硅中的扩散率和溶解度：一个计算研究

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

Acta Materialia

Pub Date : 2025-11-28 DOI: 10.1016/j.actamat.2025.121703

Kashi N. Subedi , Giridhar Nandipati , Ayoub Soulami , David J. Senor , Ria Meston , Michael Hua , Krishna Chaitanya Pitike

The life cycle of tritium in a fusion device is a critical challenge due to its high mobility in metals and potential for environmental contamination. Amorphous silica, a–SiO₂, based coatings and composites are being considered as tritium-facing materials. However, atomic-scale diffusion mechanisms of tritium in defective a–SiO₂ remain unexplored. In this study, we employ a multiscale modeling framework — combining Density Functional Theory (DFT), graph-theoretical kinetic Monte Carlo (GT-KMC) simulations, and analytical models — to investigate the tritium diffusivity and solubility in a–SiO₂. We find that tritium diffusivity follows Arrhenius behavior in defect-free a–SiO₂, with an effective migration energy of

0.20

eV

. Structural defects, such as edge-sharing SiO₄ tetrahedra, and dangling oxygen bonds alter Arrhenius behavior, leading to a temperature-dependent migration energy. Edge-sharing tetrahedra act as shallow traps, reducing diffusivity at low temperatures, while dangling oxygen bonds serve as deep traps with barriers exceeding

3.0

eV

, suppressing tritium mobility by orders of magnitude. Additionally, we assess hydrogen isotope solubility in a–SiO₂ using a chemical equilibrium model based on DFT-derived properties. This model shows excellent agreement with the experimental data for hydrogen and deuterium solubility in a–SiO₂ at standard pressure and predicts a significant decrease under low partial pressures relevant to fusion. At room temperature and

1 \times 1 0^{- 4}

Torr

pressure, tritium solubility is decreased by 3–4 orders of magnitude compared to atmospheric pressure. These insights provide a fundamental understanding of tritium permeation in a–SiO₂, highlighting the role of atomic-scale defects and providing guidance for optimizing permeation barrier materials for fusion applications.

由于氚在金属中的高迁移率和潜在的环境污染，聚变装置中的氚的生命周期是一个关键的挑战。无定形二氧化硅，a-SiO2，基涂层和复合材料被认为是面向氚的材料。然而，氚在缺陷a-SiO2中的原子尺度扩散机制尚不清楚。在这项研究中，我们采用多尺度建模框架-结合密度泛函理论（DFT），图形理论动力学蒙特卡罗（tg - kmc）模拟和分析模型-来研究氚在a - sio2中的扩散率和溶解度。在无缺陷的a - sio2中，氚的扩散率符合Arrhenius行为，迁移能为0.20 eV。结构缺陷，如边沿共享的SiO4四面体和悬垂的氧键，改变了Arrhenius行为，导致了温度依赖的迁移能。边缘共享四面体作为浅圈闭，在低温下降低了扩散系数，而悬垂氧键是深圈闭，其势垒超过3.0 eV，抑制了氚的迁移率。此外，我们利用dft衍生的性质，通过化学平衡模型评估了氢同位素在a - sio2中的溶解度。该模型与标准压力下氢和氘在a - sio2中的溶解度的实验数据非常吻合，并预测在与聚变相关的低分压下氢和氘在a - sio2中的溶解度会显著降低。在室温和1 ×× 10-4 Torr压力下，氚的溶解度比大气压降低了3-4个数量级。这些见解提供了对a - sio2中氚渗透的基本理解，突出了原子尺度缺陷的作用，并为优化用于聚变应用的渗透阻挡材料提供了指导。

{"title":"Diffusivity and solubility of tritium in amorphous silica: A computational study","authors":"Kashi N. Subedi , Giridhar Nandipati , Ayoub Soulami , David J. Senor , Ria Meston , Michael Hua , Krishna Chaitanya Pitike","doi":"10.1016/j.actamat.2025.121703","DOIUrl":"10.1016/j.actamat.2025.121703","url":null,"abstract":"<div><div>The life cycle of tritium in a fusion device is a critical challenge due to its high mobility in metals and potential for environmental contamination. Amorphous silica, <em>a</em>–SiO<sub>2</sub>, based coatings and composites are being considered as tritium-facing materials. However, atomic-scale diffusion mechanisms of tritium in defective <em>a</em>–SiO<sub>2</sub> remain unexplored. In this study, we employ a multiscale modeling framework — combining Density Functional Theory (DFT), graph-theoretical kinetic Monte Carlo (GT-KMC) simulations, and analytical models — to investigate the tritium diffusivity and solubility in <em>a</em>–SiO<sub>2</sub>. We find that tritium diffusivity follows Arrhenius behavior in defect-free <em>a</em>–SiO<sub>2</sub>, with an effective migration energy of <span><math><mrow><mn>0</mn><mo>.</mo><mn>20</mn></mrow></math></span>  <span><math><mi>eV</mi></math></span>, suppressing tritium mobility by orders of magnitude. Additionally, we assess hydrogen isotope solubility in <em>a</em>–SiO<sub>2</sub> using a chemical equilibrium model based on DFT-derived properties. This model shows excellent agreement with the experimental data for hydrogen and deuterium solubility in <em>a</em>–SiO<sub>2</sub> at standard pressure and predicts a significant decrease under low partial pressures relevant to fusion. At room temperature and <span><math><mrow><mn>1</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span> <!--> <span><math><mi>Torr</mi></math></span> pressure, tritium solubility is decreased by 3–4 orders of magnitude compared to atmospheric pressure. These insights provide a fundamental understanding of tritium permeation in <em>a</em>–SiO<sub>2</sub>, highlighting the role of atomic-scale defects and providing guidance for optimizing permeation barrier materials for fusion applications.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"304 ","pages":"Article 121703"},"PeriodicalIF":9.3,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145611454","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

Fe2Mo3O8/MoS2 enhanced leaf-like Co3O4 heterostructures: A superior bifunctional catalyst for rechargeable Zn-Air batteries Fe2Mo3O8/MoS2增强叶状Co3O4异质结构：一种优良的双功能可充电锌空气电池催化剂

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

Acta Materialia

Pub Date : 2025-11-28 DOI: 10.1016/j.actamat.2025.121776

Yong-song Tan , Shuwei Wu , Shize Li , Dajiang Kuang , Felice Torrisi , Chaoxia Wang

The development of high-performance bifunctional electrocatalysts is essential for advancing rechargeable zinc–air batteries (ZABs), particularly to overcome the sluggish kinetics of oxygen reduction (ORR) and oxygen evolution (OER) reactions at the air electrode. Here we propose a bifunctional Fe₂Mo₃O₈/MoS₂ (Fe-Mo) catalyst anchored to the surface of carbon cloth (CC) with leaf-like Co₃O₄ as the Fe₂Mo₃O₈/MoS₂@ Co₃O₄ /CC (Fe-Mo@Co-CC) electrode with effective bifunctional catalytic properties. A high-temperature annealing process is employed to synthesize Fe₂Mo₃O₈ on the surface of MoS₂ sheets. Density functional theory (DFT) calculations reveal a favorable Gibbs free energy change of −546.25 kcal mol⁻¹, indicating enhanced annealing reaction thermodynamics and improved catalytic efficiency upon Fe₂Mo₃O₈ incorporation. The leaf-like Co₃O₄ structure offers a large surface area, contributing to an increased number of accessible active sites. Moreover, the collective effects between Fe-Mo and Co₃O₄ forms an efficient interface that promotes rapid electron and ion transport, thereby enhancing the overall bifunctional electrocatalytic activity. When applied in liquid-phase ZABs, the Fe-Mo@Co-CC delivers a high peak power density of 105.4 mW cm⁻² and maintains excellent cycling stability over 5000 cycles. The study emphasizes the significance of the collective effects of transition metal components and the critical role of carbon-based supports in enhancing electrocatalytic performance.

高性能双功能电催化剂的开发是推进可充电锌-空气电池（ZABs）发展的关键，特别是为了克服空气电极上氧还原（ORR）和析氧（OER）反应动力学缓慢的问题。本文提出了一种双功能Fe2Mo3O8/MoS2 （Fe-Mo）催化剂，该催化剂锚定在碳布（CC）表面，具有叶状Co3O4，作为Fe2Mo3O8/MoS2@ Co3O4 /CC （Fe-Mo@Co-CC）电极，具有有效的双功能催化性能。采用高温退火工艺在MoS2片材表面合成Fe2Mo3O8。密度泛函数理论（DFT）计算表明，加入Fe2Mo3O8后，吉布斯自由能的变化为- 546.25 kcal mol⁻¹，表明加入Fe2Mo3O8后，退火反应热力学得到增强，催化效率得到提高。叶状的Co3O4结构提供了一个大的表面积，有助于增加可访问的活性位点的数量。此外，Fe-Mo和Co3O4之间的集体效应形成了一个有效的界面，促进了电子和离子的快速传递，从而提高了整体的双功能电催化活性。当应用于液相ZABs时，Fe-Mo@Co-CC提供105.4 mW cm - 2的峰值功率密度，并在5000次循环中保持出色的循环稳定性。该研究强调了过渡金属组分集体效应的重要性以及碳基载体在提高电催化性能方面的关键作用。

{"title":"Fe2Mo3O8/MoS2 enhanced leaf-like Co3O4 heterostructures: A superior bifunctional catalyst for rechargeable Zn-Air batteries","authors":"Yong-song Tan , Shuwei Wu , Shize Li , Dajiang Kuang , Felice Torrisi , Chaoxia Wang","doi":"10.1016/j.actamat.2025.121776","DOIUrl":"10.1016/j.actamat.2025.121776","url":null,"abstract":"<div><div>The development of high-performance bifunctional electrocatalysts is essential for advancing rechargeable zinc–air batteries (ZABs), particularly to overcome the sluggish kinetics of oxygen reduction (ORR) and oxygen evolution (OER) reactions at the air electrode. Here we propose a bifunctional Fe<sub>2</sub>Mo<sub>3</sub>O<sub>8</sub>/MoS<sub>2</sub> (Fe-Mo) catalyst anchored to the surface of carbon cloth (CC) with leaf-like Co<sub>3</sub>O<sub>4</sub> as the Fe<sub>2</sub>Mo<sub>3</sub>O<sub>8</sub>/MoS<sub>2</sub>@ Co<sub>3</sub>O<sub>4</sub> /CC (Fe-Mo@Co-CC) electrode with effective bifunctional catalytic properties. A high-temperature annealing process is employed to synthesize Fe<sub>2</sub>Mo<sub>3</sub>O<sub>8</sub> on the surface of MoS<sub>2</sub> sheets. Density functional theory (DFT) calculations reveal a favorable Gibbs free energy change of −546.25 kcal mol⁻¹, indicating enhanced annealing reaction thermodynamics and improved catalytic efficiency upon Fe<sub>2</sub>Mo<sub>3</sub>O<sub>8</sub> incorporation. The leaf-like Co<sub>3</sub>O<sub>4</sub> structure offers a large surface area, contributing to an increased number of accessible active sites. Moreover, the collective effects between Fe-Mo and Co<sub>3</sub>O<sub>4</sub> forms an efficient interface that promotes rapid electron and ion transport, thereby enhancing the overall bifunctional electrocatalytic activity. When applied in liquid-phase ZABs, the Fe-Mo@Co-CC delivers a high peak power density of 105.4 mW cm<sup>−2</sup> and maintains excellent cycling stability over 5000 cycles. The study emphasizes the significance of the collective effects of transition metal components and the critical role of carbon-based supports in enhancing electrocatalytic performance.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"304 ","pages":"Article 121776"},"PeriodicalIF":9.3,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145611484","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

Oxide stress and fracture susceptibility on a surface gradient microstructure of an additively manufactured steel 增材钢表面梯度组织的氧化应力和断裂敏感性

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

Acta Materialia

Pub Date : 2025-11-28 DOI: 10.1016/j.actamat.2025.121779

Yuhao Zhou , Kai Chen , Yuling You , Xiaoqing Shang , Yugang Li , Huigang Shi , Jiaqiang Dang , Kun Zhang , Sergio Lozano-Perez , Lefu Zhang , Zhao Shen , Xiaoqin Zeng

The oxide integrity formed on metal surfaces at high-temperature critically governs the service performance. In this paper, we focus on the residual stress/strain within the multi-layer oxide to elucidate the failure formation and propose ultrasonic surface rolling process (USRP) to mitigate brittle oxide fracture in steam. Results demonstrate that USRP enhances fracture resistance of the outer micro-Fe₃O₄ and inner nano-Cr₂O₃ crystals attached on matrix. Oxide-stress analysis shows the tensile stress gradients along the Fe₃O₄ vertical growth direction can be decreased on the USRP-treated surface, and maintains an alternating compressive/tensile values approaching zero between Fe₃O₄ clusters during transverse growth, thereby enhancing Fe₃O₄ integrity. A compressive strain gradient also exists across the Cr₂O₃ layer and USRP alleviates its internal stress/strain inside. The Fe₃O₄/Cr₂O₃ interface is mutually bonded in compression relative to growth direction and the shear component at Fe₃O₄ side reduced after USRP, thus improving interfacial adhesion. Consequently, fracture on the untreated surface exhibits through-thickness cracks, while non-critical cracks after USRP. By incorporating oxide residual stress into the crystal plasticity simulation during tension, the Fe₃O₄ layer exhibits a gradient stress characteristic, with the areas near Fe₃O₄ free surface undergoing stress relaxation, while the areas adjacent to the Cr₂O₃ layer getting stress increase. Moreover, for USRP-treated surface, the matrix develops localized zones of higher strain gradients that spatially weaken interfacial incompatibility, with the strain gradient identified as the critical factor for interface decohesion. These findings offer a peculiar insight into modulating oxidation stress to enhance oxide cracking resistance in high-temperature applications.

金属表面在高温下形成的氧化物完整性对其使用性能起着至关重要的作用。本文从多层氧化层内部的残余应力/应变出发，阐述了多层氧化层失效的形成机理，并提出了采用超声表面轧制工艺（USRP）来缓解蒸汽中氧化层脆性断裂的方法。结果表明，USRP增强了表面附着在基体上的微fe3o4晶体和内部附着在基体上的纳米cr2o3晶体的抗断裂性能。氧化应力分析表明，usrp处理表面沿Fe3O4垂直生长方向的拉伸应力梯度可以减小，并且在横向生长过程中，Fe3O4簇之间的压缩/拉伸交替值接近于零，从而增强了Fe3O4的完整性。压缩应变梯度也存在于Cr2O3层上，USRP减轻了Cr2O3层内部的应力/应变。相对于生长方向，Fe3O4/Cr2O3界面在压缩方向上相互结合，USRP后Fe3O4侧的剪切分量减少，从而提高了界面附着力。因此，未经处理的表面上的断裂呈现出贯穿厚度的裂纹，而USRP后的非临界裂纹。通过将氧化残余应力纳入拉伸过程的晶体塑性模拟，Fe3O4层呈现梯度应力特征，Fe3O4自由表面附近区域应力松弛，而Cr2O3层附近区域应力增加。此外，对于usrp处理过的表面，基体会形成具有较高应变梯度的局部区域，从而在空间上减弱界面不相容性，应变梯度被认为是界面脱黏的关键因素。这些发现为在高温应用中调节氧化应力以增强抗氧化性提供了独特的见解。

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引用次数: 0

Molecular dynamics study of twisted bilayer graphene-coated silicon carbide under nanoindentation 纳米压痕下扭曲双层石墨烯涂层碳化硅的分子动力学研究

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

Acta Materialia

Pub Date : 2025-11-27 DOI: 10.1016/j.actamat.2025.121777

Bin Li, Hong Tian, Fang Li, Pei Zuo, Chen Zhong Zhao

The effect of twisted bilayer graphene (TBG) with different torsion angles (θ) as a barrier coating for 4H silicon carbide (4H-SiC) on the enhancement of hardness-toughness synergy is investigated under nanoindentation using molecular dynamics methods. We find that (i) the average elastic modulus and intrinsic hardness of TBG-coated 4H-SiC are increased by 25.1 % and 13.5 %, respectively, compared to bare 4H-SiC. (ii) In synergy with 4H-SiC substrate, the large-angle TBG coatings show superior resistance to rigid indenter penetration than the small-angle coatings due to the enhanced slipping effect by the weakened interlayer coupling, where 21.78°-TBG coating is the most effective. (iii) At θ = 21.78°, the diamond-like structure formed by the localized sp²-to-sp³ phase transition in the slip zone of TBG coating improves the hardness and significantly delays the nucleation and propagation of the dominant full dislocations with a Burgers vector of

1 / 3 < 1 \overline{2} 10 >

in 4H-SiC substrate. (iv) Despite the perforation of 21.78°-TBG coating, the sudden increase of other dislocations competing with the full dislocations further prevents damage and failure of 4H-SiC. (v) Nanoindentation behavior shows temperature insensitivity in the elastic stage but temperature sensitivity in the plastic stage, along with sensitivity to instantaneous indentation depth. The findings reveal the key role and mechanism of twisted TBG coatings in protecting 4H-SiC and other similar materials underneath from extreme high-pressure conditions.

采用分子动力学方法研究了不同扭转角（θ）的双扭曲层石墨烯（TBG）作为4H碳化硅（4H- sic）的势垒涂层在纳米压痕下对硬度-韧性协同增强的影响。我们发现(i)与裸4H-SiC相比，tbg涂层的4H-SiC的平均弹性模量和固有硬度分别提高了25.1%和13.5%。（ii）在与4H-SiC衬底协同作用下，由于层间耦合减弱，滑移效应增强，大角度TBG涂层比小角度涂层具有更强的抗刚性压头穿透能力，其中21.78°-TBG涂层效果最好。（iii）在θ = 21.78°处，TBG涂层滑移区局部sp2- sp3相变形成的类金刚石结构提高了硬度，显著延缓了4H-SiC基体中占主导地位的全位错的形核和扩展，其Burgers向量为1/3 < 12¯10 > 1/3 < 12¯10 >。（iv）尽管21.78°-TBG涂层穿孔，但与完全位错竞争的其他位错的突然增加进一步阻止了4H-SiC的损伤和失效。(v)纳米压痕行为在弹性阶段表现为温度不敏感，在塑性阶段表现为温度敏感，并对瞬时压痕深度敏感。研究结果揭示了扭曲TBG涂层在极端高压条件下保护4H-SiC和其他类似材料的关键作用和机制。

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引用次数: 0

Modeling the equilibrium vacancy concentration in multi-principal element alloys from first-principles 基于第一性原理的多主元素合金平衡空位浓度建模

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

Acta Materialia

Pub Date : 2025-11-27 DOI: 10.1016/j.actamat.2025.121752

Damien K.J. Lee , Yann L. Müller , Anirudh Raju Natarajan

Multi-principal element alloys (MPEAs), also known as high-entropy alloys, have garnered significant interest across many applications due to their exceptional properties. Equilibrium vacancy concentrations in MPEAs influence diffusion and microstructural stability in these alloys. However, computing vacancy concentrations from ab-initio methods is computationally challenging due to the vast compositional space of MPEAs and the complexity of the local environment around each vacancy. In this work, we present an efficient approach to connect electronic structure calculations to equilibrium vacancy concentrations in MPEAs through embedded cluster expansions (eCE) and rigorous statistical mechanics methods. Using first-principles calculations and Monte Carlo simulations informed by eCE, we assess the variation in vacancy formation with alloy composition and temperature. Our method is demonstrated on a nine-component MPEA comprised of elements in groups 4, 5, and 6 of the periodic table. Correlations between alloy chemistry, short-range order, and equilibrium vacancy concentrations in alloys containing up to 9 different elements are analyzed. The vacancy concentration of refractory alloys increases with the addition of group 4 elements or elements whose mixing is energetically unfavorable. The insights into vacancy behavior and the efficient computational framework presented in this study serve as a guide for the design of complex concentrated alloys with controlled vacancy concentrations.

多主元素合金（mpea），也被称为高熵合金，由于其特殊的性能，在许多应用中引起了极大的兴趣。mpea中平衡空位浓度影响合金的扩散和组织稳定性。然而，由于mpea的巨大组成空间和每个空位周围局部环境的复杂性，从从头算方法计算空位浓度在计算上具有挑战性。在这项工作中，我们提出了一种有效的方法，通过嵌入式簇扩展（eCE）和严格的统计力学方法，将电子结构计算与mpea中的平衡空位浓度联系起来。利用第一性原理计算和蒙特卡罗模拟，我们评估了空位形成随合金成分和温度的变化。我们的方法在由元素周期表的第4,5和6族元素组成的九组分MPEA上得到了证明。分析了含9种不同元素的合金中合金化学、短程有序和平衡空位浓度之间的关系。随着4族元素的加入或混合能量不利的元素的加入，耐火合金的空位浓度增加。本研究中提出的空位行为和有效计算框架的见解为设计具有控制空位浓度的复杂浓缩合金提供了指导。

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引用次数: 0

Effect of M elements on the non-Schmid slip behavior in M-Al-C 211 MAX phases M元素对M- al - c21max相非施密德滑移行为的影响

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

Acta Materialia

Pub Date : 2025-11-26 DOI: 10.1016/j.actamat.2025.121765

Zhiqiang Zhan, Miloš Dujović, Miladin Radovic, Ankit Srivastava

MAX phases are a class of atomically layered ternary compounds composed of an early transition metal (M), an A-group element (A), and carbon and/or nitrogen (X). In this work, we systematically investigate the effect of M elements on non-Schmid crystallographic slip behavior in M-Al-C 211 MAX phases. Single-crystal micropillars of Nb-, V-, and Cr-based M-Al-C 211 MAX phases were fabricated by focused ion-beam milling and tested in uniaxial compression along multiple crystallographic orientations. The comparative dataset, including that of Ti-based M-Al-C 211 MAX phases from the literature, enables a direct correlation between the extent of non-Schmid behavior and the M-site chemistry. In all four MAX phases, slip deviates from classical Schmid’s law, with the critical resolved shear stress showing an approximately linear dependence on the normal stress acting on the basal plane. The material-specific coefficients of this relation are rationalized using theoretical bond and shear strengths estimated from previously reported cleavage and generalized stacking-fault energies. These findings provide mechanistic insight into the role of transition-metal chemistry in governing slip behavior in MAX phases.

MAX相是一类由早期过渡金属(M)、a族元素(a)、碳和/或氮(X)组成的原子层状三元化合物。在这项工作中，我们系统地研究了M元素对M- al - c21max相非施密德晶体滑移行为的影响。采用聚焦离子束铣削技术制备了Nb、V和cr基m - al - c21max相的单晶微柱，并在单轴压缩条件下进行了多晶取向测试。比较数据集，包括来自文献的ti基M-Al-C 211 MAX相，使非施密德行为的程度与m位点化学之间的直接关联成为可能。在所有四个MAX阶段，滑移偏离了经典的施密德定律，临界分解剪应力与作用在基面上的正应力近似线性相关。根据先前报道的解理和广义叠层断层能估计的理论键合强度和剪切强度，对该关系的材料特定系数进行了合理化。这些发现为过渡金属化学在控制MAX相滑移行为中的作用提供了机理见解。

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引用次数: 0