Acta Materialia最新文献_第5页

In-situ phase transition in P3-type layered oxide for high-performance Na-ion cathode 高性能钠离子阴极用p3型层状氧化物原位相变研究

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

Acta Materialia

Pub Date : 2026-01-22 DOI: 10.1016/j.actamat.2026.121955

Wenhui Li, Yang Jiang, Kun Luo

P-type layered oxide materials have mesmerized great attention in view of higher security and lower price. Unfortunately, intrinsic Na⁺/vacancy ordering reorganization and deleterious structural evolution are observed in P-type materials during electrochemical processes, resulting in stepwise electrochemical profiles along with rapid capacity attenuation and poor rate capability. P3-type layered cathode material with medium-entropy cation arrangement, P3-Na_0.75[Mg_0.05Al_0.05Zn_0.08Ni_0.22Mn_0.6]O₂ (MEO), is devised and manufactured in this manuscript. The material represents smooth electrochemical profiles without apparent voltage plateaus ranging from 2.0 V to 4.5 V, revealing a specific capacity of 115 mAh g^-1. Through structural characterizations, it has been demonstrated that MEO undergoes complete solid-solution reactions throughout the entire voltage range, promoting rapid diffusion of Na⁺ ions during the reaction (10^–10 cm² s^-1). As the charging reaches to high voltage, the material undergoes an in-situ phase transformation from P3 phase to “Z” phase which is identified as an intergrowth of P-type stacking to O-type stacking. The MEO material represents outstanding electrochemical behaviors with high rate capability (∼80 mAh g^-1 at 5 C, 1 C = 150 mA g^-1) and an ultra-long cycling life (2000 cycles). In addition, the material can work properly over a varied temperature range (85 mAh g^-1 at -45 °C and 126 mAh g^-1 at 50 °C). The conclusions reported in this manuscript prove a beneficial method to suppress the complex stepwise electrochemical curves caused by the sudden P-O phase transformation in P3-type oxide cathode materials via the in-situ phase transition in order to realize outstanding electrochemical behaviors.

p型层状氧化物材料以其较高的安全性和较低的价格而备受关注。然而，p型材料在电化学过程中存在固有的Na+/空位有序重组和有害的结构演化，导致其电化学分布呈阶梯状，容量衰减快，速率性能差。本文设计并制备了中熵阳离子排列的p3型层状正极材料P3-Na0.75[Mg0.05Al0.05Zn0.08Ni0.22Mn0.6]O2 （MEO）。该材料具有光滑的电化学曲线，在2.0 V至4.5 V范围内没有明显的电压平台，显示出115 mAh g-1的比容量。通过结构表征，证明了MEO在整个电压范围内发生完整的固溶反应，促进了Na+离子在反应过程中的快速扩散（10-10 cm2 s-1）。当充电达到高电压时，材料发生原位相变，由P3相转变为Z相，这是p型堆叠向o型堆叠的共同生长。MEO材料具有优异的电化学性能，具有高倍率性能（在5℃时约80 mAh g-1, 1℃= 150 mA g-1）和超长循环寿命（2000次循环）。此外，该材料可以在不同的温度范围内正常工作（-45°C时85 mAh g-1, 50°C时126 mAh g-1）。本文的结论证明了通过原位相变来抑制p3型氧化物正极材料中P-O相变引起的复杂的逐步电化学曲线，从而实现优异的电化学性能的有益方法。

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引用次数: 0

Structural origins of thermal expansion behavior in 2D materials 二维材料热膨胀行为的结构根源

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

Acta Materialia

Pub Date : 2026-01-22 DOI: 10.1016/j.actamat.2026.121956

Yang Yang , Guangya Li , Yixin Lin , Yan Chen , Hongxiang Zong , Xiangdong Ding , Xun-Li Wang , Jun Sun

Two-dimensional (2D) materials exhibit diverse thermal expansion behavior—with coefficients spanning a broad range from negative to positive values—fundamentally challenging our understanding of thermal expansion mechanisms and creating critical uncertainties in thermal stress prediction for next-generation devices. Despite numerous experimental measurements, the fundamental structural mechanisms underlying this remarkable variability remains elusive. Here, we resolve this longstanding puzzle through systematical molecular dynamics simulations of four representative 2D materials: hBN, PbTe, graphene, and MoS₂. Our simulations reveal that thermal expansion behavior is governed by the interplay between the intrinsic chemical bond thermal expansion and out-of-plane structural flexibility. This interplay enables 2D materials to achieve thermal expansion coefficients ranging from -15.0 × 10⁻⁶ K⁻¹ to +52.4 × 10⁻⁶ K⁻¹. Crucially, we demonstrate that thickness and lateral size effects arise exclusively through modulation of out-of-plane deformation freedom, while substrate interactions operate via a dual pathway that simultaneously constrains structural flexibility and modifies intrinsic bond behavior. Our findings culminate in a universal scaling relationship between area-specific bending rigidity and thermal expansion coefficients, providing the first predictive framework for 2D material thermal behavior.

二维（2D）材料表现出不同的热膨胀行为-系数跨越从负值到正值的广泛范围-从根本上挑战了我们对热膨胀机制的理解，并在下一代设备的热应力预测中产生了关键的不确定性。尽管进行了大量的实验测量，但这种显著变化背后的基本结构机制仍然难以捉摸。在这里，我们通过系统的分子动力学模拟四种代表性的二维材料：hBN， PbTe，石墨烯和MoS 2来解决这个长期存在的难题。我们的模拟表明，热膨胀行为是由固有化学键热膨胀和面外结构柔性之间的相互作用所控制的。这种相互作用使二维材料的热膨胀系数从-15.0 × 10⁻⁶K⁻¹到+52.4 × 10⁻⁶K⁻¹。至关重要的是，我们证明了厚度和横向尺寸效应仅通过调制面外变形自由产生，而基材相互作用通过双重途径同时限制结构灵活性和改变固有键行为。我们的研究结果最终得出了区域特定弯曲刚度和热膨胀系数之间的普遍标度关系，为二维材料热行为提供了第一个预测框架。

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引用次数: 0

Interstitial nitrogen-engineered square-planar Ni surfaces enabling efficient hydrogenation 间隙氮工程的方形平面Ni表面实现高效氢化

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

Acta Materialia

Pub Date : 2026-01-22 DOI: 10.1016/j.actamat.2026.121954

Yinghui Pu , Yiming Niu , Tongtong Gao , Junnan Chen , Bingsen Zhang

Atomically precise engineering of nanocatalyst surfaces is critical for advancing heterogeneous catalysis, yet achieving both structural uniformity and electronic tunability remains challenging. Here, we report an interstitial atom-mediated strategy for constructing anti-perovskite Ni₃CuN nanocatalysts featuring square-planar Ni surfaces coordinated by nitrogen. The resulting nanoparticles adopt cubic morphologies, undergoing nitrogen-driven facet reconstruction from high-index {210}/{110} planes to thermodynamically favored {100} facets. Atomic-resolution imaging and simulations reveal that these surfaces preferentially expose Ni-N arrangements on (

\bar{1}

00) terminations, in contrast to Ni-Cu configurations on (100) facets. This well-defined surface architecture, characterized by expanded Ni-Ni distances and electron-deficient Ni sites, leads to a substantial enhancement in acetylene hydrogenation selectivity (from 25.5% to 80.1%), while maintaining or surpassing the intrinsic activity of pure Ni and exhibiting excellent stability over 110 h of testing. These findings establish an interstitial atom-based strategy for tailoring catalytic nanostructures with precise control over surface geometry and electronic structure.

纳米催化剂表面的原子精确工程对于推进多相催化至关重要，但实现结构均匀性和电子可调性仍然具有挑战性。在这里，我们报道了一种间隙原子介导的策略，用于构建具有方形平面Ni表面和氮配位的反钙钛矿Ni3CuN纳米催化剂。所得纳米颗粒采用立方形态，经过氮驱动的面重构，从高折射率{210}/{110}平面到热力学有利的{100}面。原子分辨率成像和模拟显示，与（100）面上的Ni-Cu配置相比，这些表面优先暴露（1¯00）端部的Ni-N排列。这种明确的表面结构，以扩大Ni-Ni距离和缺乏电子的Ni位点为特征，导致乙炔加氢选择性大幅提高（从25.5%提高到80.1%），同时保持或超过纯Ni的固有活性，并在110小时的测试中表现出优异的稳定性。这些发现建立了一种基于间隙原子的策略，可以通过精确控制表面几何形状和电子结构来定制催化纳米结构。

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引用次数: 0

Direct measurement of the Gibbs free energy of mixing via atom probe tomography 用原子探针层析成像直接测量混合的吉布斯自由能

IF 9.4 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-22 DOI: 10.1016/j.actamat.2026.121950

Jianshu Zheng, Rüya Duran, Parisha Diwan, Guido Schmitz, Sebastian M. Eich

The concept of thermodynamic free energy plays a central role across various disciplines, providing critical insights into system dynamics, energy flow, and sustainability. In materials science, Gibbs free energies are typically determined through phase diagram modeling, which relies on a broad range of thermodynamic data. This process requires the investigation of well-equilibrated materials, a task that can be time-consuming or even impractical for systems with low mobility. In this study, we introduce a novel methodology for extracting the composition dependence of the Gibbs free energy of mixing from local composition fluctuations in solids using atom probe tomography (APT). We present both the theoretical framework and practical implementation through computational simulations, as well as experimental validation using APT data from Cu–Ni alloys. The experimental phase diagram constructed from the resulting Gibbs free energy of mixing shows excellent agreement with CALPHAD-based predictions. This approach provides superior accuracy and efficiency, as equilibration on the nanometer scale can be achieved in a relatively short time. It holds promising potential for application to multi-component solids, liquids, and organic systems, particularly with emerging techniques like cryo-APT.

热力学自由能的概念在各个学科中发挥着核心作用，为系统动力学、能量流和可持续性提供了关键的见解。在材料科学中，吉布斯自由能通常是通过相图建模来确定的，这依赖于广泛的热力学数据。这一过程需要对平衡良好的材料进行研究，对于低迁移率的系统来说，这是一项耗时甚至不切实际的任务。在这项研究中，我们引入了一种新的方法，利用原子探针断层扫描（APT）从固体的局部成分波动中提取混合吉布斯自由能的成分依赖性。我们通过计算模拟提出了理论框架和实际实现，并利用Cu-Ni合金的APT数据进行了实验验证。由得到的混合吉布斯自由能构建的实验相图与基于calphad的预测结果非常吻合。这种方法提供了优越的精度和效率，因为在纳米尺度上的平衡可以在相对较短的时间内实现。它在多组分固体、液体和有机系统中具有广阔的应用前景，特别是与cryo-APT等新兴技术相结合。

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引用次数: 0

Multi-block element modulation enables high temperature superconductivity in quaternary hydrides at low pressures 多块元件调制使低温下的季氢化物具有高温超导性

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

Acta Materialia

Pub Date : 2026-01-21 DOI: 10.1016/j.actamat.2026.121953

Pengye Liu , Mingyang Du , Tian Cui , Zhao Liu

Hydrides synthesis guided by structural design has significantly advanced the exploration for high-temperature superconductors but most hydrides still require extremely high pressures, which hinders their practical applications. Here, we propose a design strategy based on alloyed A15 frameworks, guided by chemical bonding principles and the strategic tuning of elements from different blocks of the periodic table, through which a series of superconducting quaternary XYZ₂H₁₂ hydrides were constructed. First-principles calculations identified six thermodynamically stable hydrides out of 80 candidates at 20 GPa, with GaAlZr₂H₁₂ and GaAlHf₂H₁₂ exhibiting T_c of 74 K and 69 K, respectively. Notably, the T_c of GaAlZr₂H₁₂ increases to 79 K at 15 GPa, exceeding the temperature of liquid nitrogen. Importantly, we reveal that the incorporation of p- and d-block elements enhances the density of states at the Fermi level and induces phonon softening via Fermi surface nesting, thereby significantly enhancing electron-phonon coupling strength. And strong electron-phonon matrix elements, primarily driven by hydrogen vibrations, significantly contribute to boost superconductivity in GaAlZr₂H₁₂ and GaAlHf₂H₁₂. Our study demonstrates that the bonding-guided approach combined with multiblock elemental tuning strategy offers an effective route for designing stable hydride superconductors, while providing guidance for realizing high-T_c superconductor under experimentally accessible low pressures.

以结构设计为指导的氢化物合成极大地推进了对高温超导体的探索，但大多数氢化物仍然需要极高的压力，这阻碍了它们的实际应用。在此，我们提出了一种基于合金A15框架的设计策略，以化学键原理和元素周期表不同区块元素的策略调整为指导，通过该策略构建了一系列超导XYZ2H12四元氢化物。第一性原理计算确定了80种候选氢化物中的6种，其中GaAlZr2H12和GaAlHf2H12的Tc分别为74 K和69 K。值得注意的是，在15 GPa时，GaAlZr2H12的Tc升高到79 K，超过了液氮温度。重要的是，我们揭示了p和d块元素的结合增强了费米能级的态密度，并通过费米表面嵌套诱导声子软化，从而显著增强了电子-声子耦合强度。由氢振动驱动的强电子-声子矩阵元素对GaAlZr2H12和GaAlHf2H12的超导性有显著的促进作用。我们的研究表明，结合多块元素调谐策略的键导方法为设计稳定的氢化物超导体提供了有效的途径，同时为在实验可及的低压下实现高tc超导体提供了指导。

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引用次数: 0

Discovery and characterization of a silicon aluminum scandate (SAS) material 硅铝酸盐（SAS）材料的发现与表征

IF 9.4 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2026-01-20 DOI: 10.1016/j.actamat.2026.121949

Kevin Yu, Jamesa Stokes, Kunal K. Jha, Bryan Harder, Hosea M. Nelson, Katherine T. Faber

A newly discovered doped silicon aluminum scandate (SAS) phase was successfully isolated and synthesized. Microcrystal electron diffraction was employed to determine the doped SAS crystal structure, revealing a triclinic (P1¯) unit cell with the nominal formula Si2Al2Sc14O28 with minority dopants of CaO, MgO, Fe2O3, and TiO2. Powder X-ray diffraction and Rietveld refinement confirmed the structure of the doped SAS material. Electron-probe microanalysis and solid-state nuclear magnetic resonance were used to better understand the composition and local structure of the doped SAS phase. The results indicated that there are extensive cation substitutions within the doped SAS material. Differential thermal analysis on doped SAS demonstrated that the material is thermally stable up to 2150°C, suggesting potential for refractory applications. Additional characterization, enabled by the solved structure of doped SAS, focused on relevant properties for refractory materials. The thermal expansion behavior of the doped SAS material was evaluated using high-temperature, in situ X-ray diffraction, while the reaction pathway for SAS formation was determined using a combination of high-temperature X-ray diffraction and annealing experiments. Ultimately, this study defines the structure, composition, and thermal behavior of the doped SAS material, while also highlighting the utility of microcrystal electron diffraction for structure determination of complex oxide phases.

成功地分离并合成了一种新发现的掺杂硅铝酸盐（SAS）相。采用微晶电子衍射法测定了掺杂的SAS晶体结构，得到了一个三斜（P1¯）的晶胞，其公称公式为Si2Al2Sc14O28，少量掺杂了CaO、MgO、Fe2O3和TiO2。粉末x射线衍射和Rietveld细化证实了掺杂SAS材料的结构。利用电子探针微分析和固态核磁共振技术更好地了解掺杂SAS相的组成和局部结构。结果表明，掺杂的SAS材料中存在广泛的阳离子取代。对掺杂SAS的差热分析表明，该材料在2150°C下热稳定，表明其具有耐火材料应用的潜力。通过求解掺杂SAS的结构，进一步表征了耐火材料的相关性质。利用高温原位x射线衍射评价了掺杂SAS材料的热膨胀行为，同时利用高温x射线衍射和退火实验相结合的方法确定了SAS形成的反应途径。最后，本研究确定了掺杂SAS材料的结构、组成和热行为，同时也强调了微晶电子衍射在复杂氧化相结构测定中的应用。

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引用次数: 0

Hydride precipitation stresses governing autocatalytic nucleation and stacking interaction in zirconium alloys: Phase-field modeling and HR-EBSD determination 锆合金中控制自催化成核和堆积相互作用的氢化物沉淀应力：相场建模和HR-EBSD测定

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

Acta Materialia

Pub Date : 2026-01-20 DOI: 10.1016/j.actamat.2026.121951

Runhao Zhang , Yao Wang , Dayong An , Xuchen Zhang , Shuyuan Zhang , Senmao Liang , Hao Xiang , Chao Yang , Weijia Gong

The local stress field in α-Zr matrix induced by δ-hydride precipitation is known to affect hydride microstructure, whereas the underlying mechanism remains ambiguous. This study exploits phase-field modeling of six δ-variants corresponding to potential shearing directions for the α-δ transformation to investigate influences of precipitation stresses on the nucleation and interaction behaviors of hydride platelets, in association with high angular-resolution electron backscatter diffraction (HR-EBSD) determination. Both the modeling and experimental results demonstrate that the precipitation stresses are characterized as significant concentration of triaxial tension and the

{0001}_{α} {< 10 - 10 >}_{α}

shear component in the vicinity of hydride tips. This characteristic of stress distribution is further identified to promote autocatalytic nucleation and variant selection of daughter hydrides at tips of a pre-existing one. With respect to the pre-existing variant, the identical type and the opposite shearing variant exhibiting prevailing formation probabilities beyond the others, yet distinct nucleation sites due to stress gradient of the shear component. Hydride evolution simulations reveal that the identical variants stack into chain structures characterized by intermediate gaps yielding compressive stress, while the variants with opposite shear directions form intersections where the shear stress is effectively relieved. This work elucidates the governing influence of precipitation stresses on the autocatalytic nucleation and stacking interaction of hydrides, providing new insights into hydride formation mechanism in zirconium alloys.

α-Zr基体中δ-氢化物析出引起的局部应力场影响了氢化物的微观结构，但其作用机制尚不清楚。本研究利用α-δ转变潜在剪切方向对应的6个δ-变量相场模型，结合高角分辨电子背散射衍射（HR-EBSD）测定，研究了沉淀应力对氢化物薄片成核和相互作用行为的影响。模型和实验结果均表明，在氢化物顶端附近，析出应力表现为显著的三轴拉伸和{0001}α < 101¯0 > α{0001}α < 101¯0 > α剪切分量。这一应力分布特征被进一步鉴定为促进已存在氢化物尖端的子氢化物的自催化成核和变异选择。相对于先前存在的变体，相同类型和相反类型的剪切变体表现出比其他变体更占优势的形成概率，但由于剪切分量的应力梯度，不同的成核位置。氢化物演化模拟表明，相同的氢化物变体叠加成链状结构，其特征是中间间隙产生压应力，而剪切方向相反的氢化物变体形成交集，有效地消除了剪应力。这项工作阐明了沉淀应力对氢化物自催化成核和堆积相互作用的控制作用，为锆合金中氢化物的形成机制提供了新的见解。

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引用次数: 0

Confined necking and improved tensile ductility in heterostructured bi-metallic steels made by additive manufacturing 增材制造双金属异质结构钢的限制颈缩和提高拉伸延展性

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

Acta Materialia

Pub Date : 2026-01-20 DOI: 10.1016/j.actamat.2026.121952

Xiao Shang , Chenwei Shao , Soumya S. Dash , Lulu Guo , Joseph Agyapong , Lizhong Lang , Alec Chen , Sang Bum Yi , Tianyi Lyu , Hao Chen , Solomon Boakye-Yiadom , Yu Zou

Achieving high tensile ductility is critical for structural materials, ensuring reliable load-bearing capability and adequate formability.. Steels, the most widely used structural metals, show a wide range of elongation to failure, from a few percent to a few tens of percent. Recently, heterostructured materials (HMs) have been reported to exhibit superior tensile properties that surpass those of their homogeneous counterparts. Classical HMs with heterogeneity in the length scale less than a few hundred nanometres attribute their enhanced mechanical performance mainly to the hetero-deformation induced (HDI) hardening. However, the underlying mechanisms for HMs with mesoscale heterogeneities, i.e., in the length scale of a few hundred micrometers, are overlooked. Recent advances in additive manufacturing (AM) have provided opportunities to fabricate HMs over the mesoscale range with structural complexity. In this work, we employ the AM method to fabricate a new type of mesoscale HM: bi-metallic heterostructured steels (HSs), consisting of 316L and PH17–4 stainless steels that possess distinct tensile strength and ductility. By tuning the ratios and fractions of 316L/PH17–4, we achieve 27.3%, 11.5%, and 1.8% improvements in the tensile ductility, ultimate tensile strength, and yield strength over 316L, respectively. Such enhanced tensile properties are mainly attributed to (i) confined-necking co-deformation, where the necking of PH17–4 is confined and delayed by 316L, offering more work hardening to the whole sample, (ii) switching between necking-induced and shear-induced failure modes, and (iii) the HDI hardening effect. This study paves the way for understanding and designing bi-metallic HSs with improved tensile properties using AM methods.

在结构材料中实现高拉伸延展性是至关重要的，因为它支持可靠的承载性能和良好的成形性。钢是应用最广泛的结构金属，其延伸率到失效的范围很广，从几个百分点到几十个百分点不等。最近，异质结构材料（HMs）表现出优于同类材料的优异拉伸性能。非均质性小于几百纳米的经典材料，其力学性能的增强主要归因于异质变形诱导（HDI）硬化。然而，具有中尺度异质性的HMs的潜在机制，即几百微米的长度尺度，被忽视了。增材制造（AM）的最新进展为在结构复杂的中尺度范围内制造HMs提供了机会。在这项工作中，我们采用增材制造方法制造了一种中尺度HM：双金属异质结构钢（HSs），由316L和PH17-4不锈钢组成，具有不同的拉伸强度和延展性。通过调整316L/PH17-4的比例和分数，我们在拉伸延展性、极限拉伸强度和屈服强度方面分别比316L提高了27.3%、11.5%和1.8%。这种增强的拉伸性能主要归因于(i)局限颈缩共变形，其中PH17-4的颈缩受到316L的限制和延迟，为整个样品提供了更多的加工硬化，（ii）颈缩诱导和剪切诱导破坏模式之间的切换，以及（iii） HDI硬化效应。本研究为利用增材制造方法理解和设计具有改进拉伸性能的双金属高速钢铺平了道路。

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引用次数: 0

Solute co-segregation mechanisms at low-angle grain boundaries in magnesium: A combined atomic-scale experimental and modeling study 镁低角晶界处溶质共偏析机制：原子尺度实验与模型研究的结合

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

Acta Materialia

Pub Date : 2026-01-20 DOI: 10.1016/j.actamat.2026.121947

Risheng Pei , Joé Petrazoller , Achraf Atila , Simon Arnoldi , Lei Xiao , Xiaoqing Liu , Hexin Wang , Sandra Korte-Kerzel , Stéphane Berbenni , Thiebaud Richeton , Julien Guénolé , Zhuocheng Xie , Talal Al-Samman

Solute segregation at low-angle grain boundaries (LAGBs) critically affects the microstructure and mechanical properties of magnesium (Mg) alloys. In modern alloys containing multiple substitutional elements, understanding solute-solute interactions at microstructural defects becomes essential for alloy design. This study investigates the co-segregation mechanisms of calcium (Ca), zinc (Zn), and aluminum (Al) at a LAGB in a dilute Mg-0.23Al-1.00Zn-0.38Ca (AZX010) alloy by combining atomic-scale experimental and modeling techniques. Three-dimensional atom probe tomography (3D-APT) revealed significant segregation of Ca, Zn, and Al at the LAGB, with Ca forming linear segregation patterns along dislocation arrays characteristic of the LAGB. Clustering analysis showed increased Ca–Ca pairs at the boundary, indicating synergistic solute interactions. Atomistic simulations and elastic dipole calculations demonstrated that larger Ca atoms prefer tensile regions around dislocations, while smaller Zn and Al atoms favor compressive areas. These simulations also found that Ca–Ca co-segregation near dislocation cores is energetically more favorable than other solute pairings, explaining the enhanced Ca clustering observed experimentally. Thermodynamic modeling incorporating calculated segregation energies and solute-solute interactions accurately predicted solute concentrations at the LAGB, aligning with experimental data. The findings emphasize the importance of solute interactions at dislocation cores in Mg alloys, offering insights for improving mechanical performance through targeted alloying and grain boundary engineering.

低角晶界处的溶质偏析严重影响镁合金的显微组织和力学性能。在含有多种取代元素的现代合金中，了解微观结构缺陷处的溶质-溶质相互作用对合金设计至关重要。本研究采用原子尺度实验和模型技术相结合的方法研究了稀Mg-0.23Al-1.00Zn-0.38Ca （AZX010）合金中钙（Ca）、锌（Zn）和铝（Al）在LAGB中的共偏析机理。三维原子探针断层扫描（3D-APT）显示，Ca、Zn和Al在LAGB处存在明显的偏析，Ca沿LAGB的位错阵列形成线性偏析模式。聚类分析表明，边界处Ca-Ca对增加，表明溶质相互作用协同。原子模拟和弹性偶极子计算表明，较大的Ca原子倾向于位错周围的拉伸区，而较小的Zn和Al原子倾向于压缩区。这些模拟还发现，在位错核心附近的Ca - Ca共偏析在能量上比其他溶质对更有利，这解释了实验观察到的Ca聚类增强。热力学模型结合了计算的偏析能和溶质-溶质相互作用，准确地预测了LAGB的溶质浓度，与实验数据一致。研究结果强调了镁合金位错核心处溶质相互作用的重要性，为通过定向合金化和晶界工程改善机械性能提供了见解。

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引用次数: 0

In-situ observations of misfit dislocation motion in AlSb/GaSb dislocation filter layer structures AlSb/GaSb位错滤层结构错配位错运动的原位观察

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.2026.121946

Karl Graser , Audrey Gilbert , Jean-Baptiste Rodriguez , Eric Tournié , Achim Trampert

The dislocation dynamics in epitaxially strained GaSb/AlSb/GaSb heterostructures grown on a Si(001) substrate via molecular beam epitaxy have been studied by means of scanning transmission electron microscopy. The 100 nm-thick AlSb layer – intentionally inserted as dislocation filter – is partially relaxed by bending pre-existing threading dislocations of the GaSb buffer into the interface with AlSb, creating a complex network of misfit dislocations. In addition to the expected misfit dislocation lines along the orthogonal 〈110〉 directions, irregular curved lines are also detected. Plan-view lamellae of the as-grown heterostructure were annealed in-situ in the microscope at temperatures well above the growth temperature to observe the propagation and interaction of the dislocations in real time. It was found that the (thermally activated) motion of misfit dislocations occurs independently of their Burgers vectors within the interface plane, which is not one of the primary slip systems of zinc-blende crystal structure, and without affecting the threading dislocation configuration in the filter layer. This unusual dislocation motion at this later stage of plastic relaxation (already 50% of lattice mismatch is relieved in the as-grown heterostructure AlSb layer) can only be explained by a non-conservative dislocation climb process on the one hand, and a vacancy-assisted slip on the other hand as it was recently discovered using molecular dynamics modeling. The results provide deeper insights into the thermal activation of dislocations in epitaxially strained systems and reveal potential for re-examining the conditions of those epi‑layers as dislocation filters.

用扫描透射电镜研究了分子束外延生长在Si（001）衬底上的外延应变GaSb/AlSb/GaSb异质结构中的位错动力学。100 nm厚的AlSb层（故意插入作为位错过滤器）通过将GaSb缓冲液中预先存在的螺纹位错弯曲到AlSb的界面中，从而部分放松，从而形成一个复杂的错配位错网络。除了沿正交< 110 >方向的预期错配位错线外，还检测到不规则的曲线。在远高于生长温度的温度下，在显微镜下对生长异质结构的平面层片进行原位退火，实时观察位错的扩展和相互作用。发现失配位错的（热激活）运动与界面平面内的Burgers矢量无关，不是锌-闪锌矿晶体结构的主要滑移体系之一，也不影响滤层中的螺纹位错构型。这种不寻常的位错运动在塑性松弛的后期阶段（在生长的异质结构AlSb层中已经减轻了50%的晶格错配）只能用非保守位错爬升过程和空位辅助滑移来解释，这是最近使用分子动力学模型发现的。这些结果为外延应变系统中位错的热激活提供了更深入的见解，并揭示了重新检查这些外延层作为位错过滤器的条件的潜力。

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