International Journal of Plasticity最新文献_第7页

Anisotropic detwinning behaviors in nanotwinned aluminum: An atomistic simulation study 纳米孪晶铝的各向异性脱孪行为：原子模拟研究

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-25 DOI: 10.1016/j.ijplas.2025.104568

Peng Jing , Bin Shao , Yingying Zong , Hongxi Liu

The excellent strength and toughness of nanotwinned Al, which can be further improved, make it suitable for interconnects in flexible electronic components. The key is to fully understand the precise physical nature of detwinning at extremely small twin boundary spacings. In this study, molecular dynamics simulations were conducted to investigate the anisotropic detwinning behaviors in nanotwinned Al. When there is no resolved shear stress on the twin boundaries, simulation results indicate that detwinning does not occur upon yield, but only after twin rotation. Twin rotation and the local interaction between dislocations drive detwinning. Directional dislocation propagation induces twin rotation, ultimately resulting in the formation of subgrains and shear bands. The overall intensity of detwinning decreases with increasing twin boundary spacing. When the loading direction is oriented at a 45° angle to the twin boundaries, almost exclusively detwinning dislocations are activated throughout the entire deformation process, a behavior that is independent of twin boundary spacing. The grains within nanotwinned polycrystals exhibit anisotropic detwinning behaviors. The influence of detwinning on mechanical properties is not apparent until a substantial degree of detwinning has accumulated. Detwinning is enhanced at higher temperatures but suppressed under higher strain rates. The kinetic analysis of the detwinning process demonstrates that the mechanisms identified in this study are applicable to experimental conditions. A model was proposed to describe the relationship between the twin rotation angle and twin boundary spacing. These findings further deepen the understanding of the anisotropic detwinning mechanisms in nanotwinned metals.

纳米孪晶铝具有优异的强度和韧性，并且还可以进一步提高，使其适用于柔性电子元件的互连。关键是要充分了解在极小的孪晶边界间距处的确切物理性质。本研究通过分子动力学模拟研究了纳米孪晶Al的各向异性脱孪行为。模拟结果表明，当孪晶边界上没有可分辨的剪切应力时，脱孪不会在屈服时发生，而是在孪晶旋转后才发生。孪晶旋转和位错之间的局部相互作用驱动孪晶。定向位错的传播引起孪晶旋转，最终导致亚晶和剪切带的形成。总体脱孪强度随孪晶边界间距的增大而减小。当加载方向与孪晶界成45°角时，整个变形过程中几乎只激活了去孪位错，这一行为与孪晶界间距无关。纳米孪晶中的晶粒表现出各向异性脱孪行为。脱孪生对机械性能的影响在积累了相当程度的脱孪生后才显现出来。在较高的温度下，去孪生得到增强，但在较高的应变速率下被抑制。对脱孪生过程的动力学分析表明，本研究确定的机理适用于实验条件。提出了一种描述孪晶界距与孪晶界角关系的模型。这些发现进一步加深了对纳米孪晶金属各向异性脱孪机制的理解。

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引用次数: 0

Chemical ordering and generalized stacking fault energy in high-entropy alloys: Simulation and multimodal machine learning 高熵合金的化学有序和广义层错能：模拟和多模态机器学习

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-24 DOI: 10.1016/j.ijplas.2025.104567

Jianyu Zhang , Dingqi Zhao , Junwei Qiao , Yong-Wei Zhang

Stacking Fault Energy (SFE) is a critical microstructural factor governing deformation mechanisms in high-entropy alloys (HEAs). While traditional computational techniques succeed in understanding SFE, they remain extremely time-consuming. Traditional SFE prediction models, relying solely on composition, cannot describe local atomic clustering effects on SFE. Therefore, developing specialized machine learning (ML)-accelerated methods capable of predicting SFE is crucial for guiding high-performance alloy design.

Multiple studies have demonstrated that the variables influencing the SFE of alloys are not limited to alloy composition; short-range ordering (SRO) is equally important. This study used MD simulations to investigate the combined influence of composition and SRO in Cr_x(FeCoNi)_1-x HEAs. It was found that after the introduction of SRO, the average SFE increased by 21.2 ± 7.1 mJ/m² (2.7-fold higher than the random solid solution (RSS) state), and the yield strength was significantly enhanced by 3 GPa (1.2-fold higher than the RSS state). This is attributed to Cr clustering around dislocations in the SRO state.

SRO and alloy composition are simultaneously important influencing factors for SFE, and traditional models that rely on single-variable predictions struggle to capture the coupling effects of these two factors. Therefore, this study maps compositional variables and the degree of ordering into structural features and image information, which serve as concurrent inputs for a neural network, to construct an efficient predictive model via a multimodal machine learning algorithm. This predictive method is 2 orders of magnitude faster than traditional models, providing an efficient tool for HEAs design and microscopic deformation mechanism studies.

层错能（SFE）是控制高熵合金（HEAs）变形机制的重要微观组织因素。虽然传统的计算技术在理解SFE方面取得了成功，但它们仍然非常耗时。传统的SFE预测模型仅依赖于成分，无法描述局部原子聚类效应对SFE的影响。因此，开发能够预测SFE的专用机器学习（ML）加速方法对于指导高性能合金设计至关重要。多项研究表明，影响合金SFE的变量并不局限于合金成分；短程订购（SRO）同样重要。本研究采用MD模拟研究了组分组成和SRO对Crx(FeCoNi)1-x HEA的综合影响。结果表明，引入SRO后，材料的平均SFE提高了21.2±7.1 mJ/m²（比随机固溶体（RSS）状态高2.7倍），屈服强度显著提高了3 GPa（比随机固溶体（RSS）状态高1.2倍）。这是由于在SRO状态下，Cr聚集在位错周围。SRO和合金成分同时是SFE的重要影响因素，依赖单变量预测的传统模型难以捕捉这两个因素的耦合效应。因此，本研究将组成变量和排序程度映射到作为神经网络并发输入的结构特征和图像信息中，通过多模态机器学习算法构建高效的预测模型。该预测方法比传统模型快2个数量级，为HEA设计和微观变形机理研究提供了有效的工具。

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引用次数: 0

A cohesive law-based fracture phase field model for microcrack initiation and propagation in shape memory alloys subjected to a cyclic loading 基于内聚规律的形状记忆合金微裂纹萌生与扩展断裂相场模型

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-23 DOI: 10.1016/j.ijplas.2025.104557

Junyuan Xiong , Bo Xu , Jiachen Hu , Chao Yu , Guozheng Kang

This study proposes a cohesive law-based fracture phase field model combined with crystal plasticity theory to elucidate the complex microcrack initiation and propagation of shape memory alloys (SMAs) subjected to cyclic loading. A traction-separation relationship that can be experimentally calibrated is incorporated into the cohesive law of the proposed model, and the degradation of the fracture toughness caused by the localized accumulation of plastic deformation (captured by the crystal plasticity theory) is quantified through a degradation function. The simulation results demonstrate that the relatively high localized accumulated plasticity (leading to a damage accumulation) and elastic energy (providing the main driving force) can lead to microcrack initiation and propagation in NiTi SMAs during cyclic loading. When both the accumulated plasticity and elastic energy are relatively high in a local region, the propagation rate of microcracks in such a region is significantly higher than that of the microcracks in other regions or with only one dominant factor (e.g., accumulated plasticity or elastic energy). The different microstructural evolutions of austenitic and martensitic NiTi SMAs induce distinct distributions and magnitudes of elastic energy and accumulated plasticity, which drive their different microcrack evolutions. The synergistic influence of elastic energy and accumulated plasticity on microcrack evolution is effectively described by the proposed model. The simulated microcrack evolution features are in qualitative agreement with the corresponding experimental results of NiTi SMAs, validating the rationality of the proposed model and providing solid support for the investigation of the crack behavior and fracture-resistant design of SMAs and their devices.

结合晶体塑性理论，提出了基于内聚规律的断裂相场模型来解释形状记忆合金在循环载荷作用下的复杂微裂纹萌生和扩展过程。将可通过实验标定的牵引-分离关系纳入该模型的内聚规律，并通过退化函数量化由局部塑性变形积累引起的断裂韧性退化（由晶体塑性理论捕获）。模拟结果表明，在循环加载过程中，较高的局部累积塑性（导致损伤累积）和弹性能（提供主要驱动力）是导致NiTi sma微裂纹萌生和扩展的主要原因。当某一局部区域的累积塑性和弹性能都较高时，该区域的微裂纹扩展速率明显高于其他区域的微裂纹扩展速率，或者只有一个主导因素（如累积塑性或弹性能）的微裂纹扩展速率明显高于其他区域。奥氏体和马氏体NiTi sma的不同组织演化导致其弹性能和累积塑性的不同分布和大小，从而驱动其不同的微裂纹演化。该模型有效地描述了弹性能和累积塑性对微裂纹演化的协同影响。模拟的微裂纹演化特征与相应的NiTi SMAs实验结果在定性上一致，验证了所提模型的合理性，为SMAs及其器件的裂纹行为研究和抗断裂设计提供了坚实的支撑。

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引用次数: 0

Strengthening mechanisms of Mo–Nb–Ti and Ta–Nb–Ti complex-concentrated alloys: Data-driven insights from atomic descriptors and short-range order Mo-Nb-Ti和Ta-Nb-Ti络合物浓缩合金的强化机制：来自原子描述符和短程有序的数据驱动见解

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-20 DOI: 10.1016/j.ijplas.2025.104556

Taeyeop Kim , Daegun You , Dongwoo Lee

The design of refractory complex-concentrated alloys (RCCAs) requires a comprehensive understanding of how alloying elements govern microstructure and mechanical response. Here, we report an integrated approach combining high-throughput experiments on Mo-Nb-Ti and Ta-Nb-Ti thin-film alloy libraries with molecular dynamics simulations to examine short range order (SRO). Composition dependent X-ray diffraction and electron microscopy investigations reveal that Mo-Nb-Ti alloys maintain fine grain sizes with minimal temperature dependence, whereas Ta-Nb-Ti alloys undergo substantial grain growth at elevated temperature. Nanoindentation mapping shows that Mo-Nb-Ti alloys consistently exhibit higher hardness and hardness-to-modulus ratios than Ta-Nb-Ti alloys, with strengthening largely affected by solid-solution effects. In contrast, the hardness reduction in Ta-Nb-Ti films deposited at high temperature is directly correlated with grain coarsening. Molecular dynamics simulations further demonstrate that SRO plays a critical role in strengthening and plasticity.

设计难熔复合浓缩合金（RCCAs）需要对合金元素如何控制微观结构和力学响应有全面的了解。在这里，我们报告了一种综合方法，将Mo-Nb-Ti和Ta-Nb-Ti薄膜合金库的高通量实验与分子动力学模拟相结合，以研究短程有序（SRO）。成分相关的x射线衍射和电子显微镜研究表明，Mo-Nb-Ti合金在温度依赖性最小的情况下保持细小的晶粒尺寸，而Ta-Nb-Ti合金在高温下晶粒生长明显。纳米压痕图显示，Mo-Nb-Ti合金的硬度和硬度模量比始终高于Ta-Nb-Ti合金，强化主要受固溶效应影响。高温沉积的Ta-Nb-Ti薄膜硬度降低与晶粒粗化直接相关。分子动力学模拟进一步证明了SRO在强化和塑性方面起着至关重要的作用。

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引用次数: 0

A flux boundary condition for grain boundary-dislocation interaction using all-dislocation density dynamics (ADD) 基于全位错密度动力学（ADD）的晶界-位错相互作用的通量边界条件

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-20 DOI: 10.1016/j.ijplas.2025.104554

Alireza Kalaei , Jinxin Yu , Jian Han , David J. Srolovitz , Alfonso H.W. Ngan

Grain boundaries (GBs) play a crucial role in the plasticity of polycrystalline materials, yet mesoscopic simulation methods to study their effects remain scarce. During plastic deformation, dislocations interact with GBs in various ways—they may transfer to adjacent grains, reflect back, or be absorbed—depending on the GB's properties. Past attempts to understand these effects have predominantly relied on atomistic simulation with limited spatiotemporal scales. Here, we exploit an "all-dislocation" density (ADD) dynamics framework to simulate plasticity within grains and at GBs. We derived a flux boundary condition for ADD that incorporates the dislocation density flux at the GB and implements it numerically on a rhombus mesh structure. The dislocation flux is computed using a mathematically robust framework that rigorously accounts for factors affecting slip transfer. The numerical scheme examines the effects of misorientation angle and grain size on slip transfer under constant stress, constant stress rate, and constant strain rate conditions. The results reveal that lower misorientation angles lead to higher plastic strain and mobile dislocation density. Furthermore, plastic strain is inversely proportional to the square root of the grain size, aligning with the Hall–Petch relationship. Strain hardening intensifies with increasing grain boundary misorientation, reflecting reduced slip transfer through less permeable boundaries. The study also investigates how mobility and initial dislocation density influence lattice resistance and GB strengthening, revealing transitions between hardening mechanisms. These expected results confirm that the ADD framework is appropriate for mesoscopic simulation of GB effects in dislocation plasticity.

晶界在多晶材料的塑性中起着至关重要的作用，但研究其影响的介观模拟方法仍然很少。在塑性变形过程中，位错以各种方式与GB相互作用——它们可能转移到相邻的晶粒，反射回来，或被吸收——这取决于GB的性能。过去理解这些效应的尝试主要依赖于有限时空尺度的原子模拟。在这里，我们利用“全位错”密度（ADD）动力学框架来模拟晶粒内和gb的塑性。我们推导了一个包含位错密度通量的ADD通量边界条件，并在菱形网格结构上数值实现了它。位错通量的计算采用了数学上稳健的框架，严格考虑了影响滑移传递的因素。该数值方案考察了在恒定应力、恒定应力速率和恒定应变速率条件下，取向角和晶粒尺寸对滑移传递的影响。结果表明，取向角越小，塑性应变和可动位错密度越高。此外，塑性应变与晶粒尺寸的平方根成反比，符合Hall-Petch关系。应变硬化随着晶界取向偏差的增加而加剧，反映出通过渗透性较低的晶界的滑移传递减少。研究还探讨了迁移率和初始位错密度如何影响晶格电阻和GB强化，揭示了硬化机制之间的转变。这些预期结果证实了ADD框架适用于位错塑性中GB效应的介观模拟。

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引用次数: 0

A phase-field model for Mg-NiTi shape memory alloy composites incorporating multiple inelastic deformation mechanisms 考虑多种非弹性变形机制的Mg-NiTi形状记忆合金复合材料相场模型

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-19 DOI: 10.1016/j.ijplas.2025.104555

Bo Xu , Jiachen Hu , Chao Yu , Junyuan Xiong , Di Song , Chong Wang , Qianhua Kan , Qingyuan Wang , Guozheng Kang

A crystal plasticity-based phase-field model that comprehensively accounts for the inelastic deformation mechanisms of both magnesium (Mg) and NiTi shape memory alloys is proposed to describe the inelastic deformation of Mg-NiTi composites. The thermodynamic driving forces governing the inelastic deformation mechanisms are strictly derived under the framework of irreversible thermodynamics. The compressive deformation behaviors of Mg-NiTi composites with various volume fractions of superelastic and shape-memory NiTi reinforcements are simulated. The validity of the proposed phase-field model is confirmed by qualitatively comparing the experimental results with the simulated ones. The results indicate that during compression, the Mg-NiTi composites exhibit distinct deformation mechanisms depending on the reinforcement type and content. For the composites with a low superelastic NiTi content, inelastic deformation occurs through the twinning and dislocation slip of Mg phase. With a higher superelastic NiTi content, the plastic deformation of the composites is first dominated by the twinning and dislocation slip of Mg phase, followed by the martensite transformation of NiTi phase. In the shape-memory NiTi-reinforced composites, low reinforcement fractions lead to a plastic deformation dominated by the twinning and dislocation slip of Mg phase with a supplementary martensite reorientation of NiTi phase. At higher shape-memory NiTi fractions, the plastic deformation involves coordinated contributions from both phases, i.e., the twinning and dislocation slip in Mg phase, as well as the martensite reorientation and plasticity in NiTi phase. The proposed phase-field model offers a theoretical framework for simulating the microstructure-dependent mechanical behavior of Mg-NiTi composites with arbitrary phase volume fractions and morphologies, which can assist the design of high-performance Mg-NiTi composites with tunable mechanical properties through microstructure engineering, such as phase morphology optimization and texture engineering.

提出了一种综合考虑镁（Mg）和NiTi形状记忆合金非弹性变形机理的基于晶体塑性的相场模型来描述Mg-NiTi复合材料的非弹性变形。在不可逆热力学的框架下，严格推导了控制非弹性变形机制的热力学驱动力。模拟了不同体积分数的超弹性和形状记忆NiTi增强Mg-NiTi复合材料的压缩变形行为。将实验结果与仿真结果进行定性比较，验证了所提相场模型的有效性。结果表明：Mg-NiTi复合材料在压缩过程中，随增强类型和含量的不同表现出不同的变形机制；对于低超弹性NiTi含量的复合材料，非弹性变形通过Mg相的孪晶和位错滑移发生。当超弹性NiTi含量较高时，复合材料的塑性变形首先以Mg相的孪晶和位错滑移为主，其次是NiTi相的马氏体转变。在形状记忆型NiTi增强复合材料中，低强化分数导致了以Mg相的孪晶和位错滑移为主的塑性变形，并伴有NiTi相的马氏体重取向。在较高的形状记忆分数下，塑性变形涉及两相的协调贡献，即Mg相的孪晶和位错滑移以及NiTi相的马氏体重取向和塑性。所提出的相场模型为模拟具有任意相体积分数和形貌的Mg-NiTi复合材料的微观结构相关力学行为提供了理论框架，有助于通过相形貌优化和织构工程等微观结构工程设计具有可调力学性能的高性能Mg-NiTi复合材料。

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引用次数: 0

Achieving ultra-high twin density and strength in HCP materials with selectively activated twining systems 通过选择性激活缠绕系统，在HCP材料中实现超高的孪晶密度和强度

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-19 DOI: 10.1016/j.ijplas.2025.104552

Zhaowen Huang , Shuaizhuo Wang , Haotian Yan , Donghui Wen , Na Lin , Zhicheng Miao , Xiaodong Hou , Anding Wang , Yusheng Li , Yang Cao , Biao Wang

Twinning is a highly effective mechanism for enhancing the mechanical properties of hexagonal close-packed (HCP) materials. However, achieving ultra-high twin density in a scalable, time- and energy-efficient manner remains a significant challenge. In this study, the combined influence of deformation temperature and crystallographic texture on twinning system selection in commercially pure Ti were systematically investigated. Through tailored texture modification and cryogenic rolling, a high-density twin (HDT) structure with a twin volume fraction exceeds 67% was successfully fabricated. These twinning activities promoted the generation of unfavoured <a>-basal, <c>-prismatic and 〈c + a〉 pyramidal slips. The resulting HDT-Ti exhibited an ultrahigh yield strength above 950 MPa and an ultimate tensile strength around 1 GPa. This superior performance arises from multiple strengthening mechanisms, including twinning, dislocation accumulation, and grain boundary effects. Notably, the activation of twinning systems exhibited unexpected dependencies on temperature and texture: extension twins, characterized by lower twinning shear, predominated at room temperature irrespective of orientation; while compression twins, which have higher twinning shear, were significantly activated only under cryogenic conditions even in the unfavourably oriented grain. These unconventional behaviours were elucidated through electron backscatter diffraction analysis, twinning shear calculations, and atomic shuffling considerations. The findings offer new insights into twinning system selection and provide a practical, scalable route to design bulk HCP materials with tailored twin architectures and superior strength-ductility synergy.

孪生是提高六方密排材料力学性能的有效机制。然而，以可扩展、时间和节能的方式实现超高孪晶密度仍然是一个重大挑战。在本研究中，系统地研究了变形温度和晶体织构对商业纯钛孪晶体系选择的综合影响。通过定制织构改性和低温轧制，成功制备了孪晶体积分数超过67%的高密度孪晶（HDT）结构。这些孪生活动促进了不利的<；a>；-基底滑移、<；c>；-棱柱滑移和<；c+a>；金字塔滑移的产生。所得HDT-Ti具有950 MPa以上的超高屈服强度和1 GPa左右的极限抗拉强度。这种优异的性能源于多种强化机制，包括孪晶、位错积累和晶界效应。值得注意的是，孪晶系统的激活出乎意料地依赖于温度和织构：延伸孪晶，其特征是孪晶剪切较低，在室温下占主导地位，而与取向无关；压缩孪晶具有较高的孪晶剪切力，即使在不利取向晶粒中，压缩孪晶也仅在低温条件下被显著激活。这些非常规的行为是通过电子后向散射衍射分析、孪生剪切计算和原子洗牌的考虑来阐明的。该研究结果为孪生系统的选择提供了新的见解，并提供了一种实用的、可扩展的途径来设计具有定制孪生结构和卓越强度-延性协同作用的大块HCP材料。

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引用次数: 0

Twinning- and transformation-induced high cryogenic strength and ductility of the CoCrFeNi high-entropy alloy: Experiment and MD simulation CoCrFeNi高熵合金的孪生和相变高低温强度和延展性：实验和MD模拟

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-19 DOI: 10.1016/j.ijplas.2025.104553

Yuze Wu , Zhide Li , Charlie Kong , M.W. Fu , Hailiang Yu

The CoCrFeNi high-entropy alloy (HEA) processed by asymmetric cryorolling (ACR) followed by short-term annealing exhibited an exceptional strength-ductility synergy under cryogenic conditions. Compared to room temperature, the tensile strength increased from 880 to 1281 MPa, and the fracture elongation increased from 50.1 % to 89.8 %. To reveal the underlying mechanism, molecular dynamics (MD) simulations were employed to investigate the deformation processes at room and cryogenic temperatures. The simulations revealed distinct microstructural evolution pathways involving intrinsic stacking faults (ISFs), extrinsic stacking faults (ESFs), twins, and HCP phases. The combined experimental and simulation results demonstrate that twinning and HCP-phase formation are the dominant deformation mechanisms responsible for the enhanced strength and ductility at cryogenic temperatures. Under cryogenic conditions, twinning and HCP-phase formation initiated at lower strain levels. Compared with tensile deformation at room temperature, the higher flow stress and the cryogenic environment during cryogenic tensile deformation led to denser twin systems, more extensive Lomer-Cottrell (L–C) lock networks, and greater HCP-phase formation, resulting in exceptional strain-hardening capacity and ultrahigh ductility. These findings provide a comprehensive understanding of the microstructural evolution and strengthening mechanisms in HEAs under extreme conditions, offering a promising processing route for producing materials for aerospace applications with high strength and ductility.

在低温条件下，经不对称冷滚（ACR）和短期退火处理的CoCrFeNi高熵合金（HEA）表现出优异的强度-塑性协同效应。与室温相比，拉伸强度从880 MPa提高到1281 MPa，断裂伸长率从50.1%提高到89.8%。为了揭示其潜在的机制，采用分子动力学（MD）模拟研究了室温和低温下的变形过程。模拟结果显示了不同的微观结构演化路径，包括内在层错（ISFs）、外在层错（ESFs）、孪晶和HCP相。实验和模拟结果表明，孪晶和hcp相的形成是低温下强度和延性增强的主要变形机制。在低温条件下，孪晶和hcp相的形成始于较低应变水平。与室温拉伸变形相比，低温拉伸变形过程中较高的流动应力和低温环境导致孪晶体系更致密，lmer - cottrell （L-C）锁网络更广泛，hcp相形成更大，从而产生了优异的应变硬化能力和超高的塑性。这些发现为极端条件下HEAs的微观组织演变和强化机制提供了全面的理解，为生产高强度和高塑性航空航天应用材料提供了一条有前途的加工路线。

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引用次数: 0

Micromechanical analysis of stress-induced anisotropic frictional damage, spontaneous localization and post-peak snapback problem in quasi-brittle geomaterials 准脆性岩土材料应力诱导各向异性摩擦损伤、自发局部化及峰后弹回问题的细观力学分析

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-15 DOI: 10.1016/j.ijplas.2025.104549

Qi-Zhi Zhu , Qiao-Juan Yu , Jian-fu Shao , Xing-Guang Zhao

Some fundamental issues in quasi-brittle solids, such as closed-form failure description, reliable solution to anisotropic coupling equations, cracking-induced localization, post-peak mechanical response, still remain largely open. Focus here is transferred from the case of isotropic damage to more complex anisotropic frictional damage problems. The constitutive equations are formulated by applying linear homogenization to a solid matrix-microcracks heterogeneous system, whose solution actually constitutes a typical nonlinear complementary problem. Analytical solutions are found under some specific loading paths, which make it possible to perform relevant critical analyses on mechanical behaviors of quasi-brittle solid. It is interestingly found that cracks in critical families propagate predominantly, especially in the post-peak phase, by controlling material failure and leading to the localization from diffuse damage (microcracks) to one or several macro cracks. When solids tend to be brittle, there will appear a transition in mechanical response from type-I to type-II with a snap-back phase. On numerical aspects, both fully coupled- and decoupled correction schemes are developed and compared to the analytical results achieved herein.

准脆性固体的一些基本问题，如封闭型破坏描述、各向异性耦合方程的可靠解、裂纹局部化、峰后力学响应等，仍有很大的开放性。这里的重点从各向同性损伤的情况转移到更复杂的各向异性摩擦损伤问题。将线性均匀化方法应用于固体基质-微裂纹非均质系统的本构方程，该系统的解实际上是一个典型的非线性互补问题。在某些特定加载路径下找到了解析解，为准脆性固体力学行为的相关临界分析提供了可能。有趣的是，通过控制材料失效并导致从弥漫性损伤（微裂纹）局部化到一个或几个宏观裂纹，关键族裂纹主要扩展，特别是在峰后阶段。当固体趋于脆性时，力学响应会出现由i型向ii型的转变，并出现回弹阶段。在数值方面，提出了完全耦合和解耦的校正方案，并与本文的解析结果进行了比较。

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引用次数: 0

A new strategy for fabricating Mg-Al alloys with excellent strength-ductility synergy via pulse-coupled wire-arc directed energy deposition 脉冲耦合线弧定向能沉积制备具有优异强度-延展性协同效应的Mg-Al合金的新策略

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2025-11-14 DOI: 10.1016/j.ijplas.2025.104550

Yukang An , Enyu Guo , Diyang Xia , Shuo Yin , Zhirou Zhang , Wuyue Zheng , Zongning Chen , Huijun Kang , Tongmin Wang

Wire-arc directed energy deposition (W-DED) is a cost-effective additive manufacturing technology increasingly applied to the fabrication of magnesium alloy components. However, AZ-series magnesium alloys fabricated by conventional DED suffer from inadequate properties and premature failure due to stress concentration caused by coarse structure and high fraction of porosity. In this work, a high-energy pulsed arc is introduced into the W-DED of AZ31B alloy, and its effects on porosity, microstructure, mechanical properties, and deformation damage behavior are comprehensively investigated. The pulsed-coupled DED (CMT+P) process significantly enhances component densification while refining grains and precipitates by intensifying solidification dynamics and modifying solute redistribution. The AZ31B alloy fabricated by CMT+P process exhibits a superior strength-ductility synergy, with ultimate tensile strength of 262 ± 1.5 MPa along BD and 267 ± 2 MPa along TD accompanied by a total elongation of 24.7 ± 1.8 % and 25.4 ± 1.5 %, respectively. In-situ synchrotron tomography from a novel “primary damage band (PDB)” perspective reveals the competitive relationship between initial and derived pores of deformation behavior. During the progressive damage evolution, the optimized structure crucially suppresses derived pore nucleation and delays stress accumulation to enhance damage tolerance and promote uniform plastic deformation. This work provides a new strategy for fabricating high-performance Mg-Al DED components that combine high performance with superior damage resistance.

电弧定向能沉积（W-DED）是一种经济高效的增材制造技术，越来越多地应用于镁合金部件的制造。然而，传统DED法制备的az系列镁合金由于结构粗大、孔隙率高，导致应力集中，导致性能不理想、过早失效。本文将高能脉冲电弧引入AZ31B合金的W-DED中，全面研究了高能脉冲电弧对AZ31B合金的孔隙率、微观组织、力学性能和变形损伤行为的影响。脉冲耦合DED （CMT+P）工艺通过强化凝固动力学和改变溶质再分布来细化晶粒和析出相，显著提高了组分致密化程度。CMT+P工艺制备的AZ31B合金表现出优异的强度-塑性协同效应，沿双轴拉伸强度为262±1.5 MPa，沿双轴拉伸强度为267±2 MPa，总伸长率分别为24.7±1.8 %和25.4±1.5 %。从一种新颖的“初级损伤带（PDB）”角度出发的原位同步加速器断层扫描揭示了变形行为的初始和衍生孔隙之间的竞争关系。在损伤演化过程中，优化后的结构对孔隙成核和应力积累起到关键抑制作用，从而提高损伤容限，促进均匀塑性变形。这项工作为制造高性能Mg-Al DED组件提供了一种新的策略，该策略将高性能与优异的抗损伤性结合起来。

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