International Journal of Plasticity最新文献_第6页

A physics-based microscale model for predicting Coble creep deformation: Incorporating stress–diffusion interactions and effects of polycrystalline morphology 预测电缆蠕变的一个基于物理的微尺度模型：结合应力扩散相互作用和多晶形态的影响

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-02-01 Epub Date: 2026-01-11 DOI: 10.1016/j.ijplas.2026.104609

Kota Sagara , Mitsuhiro Ito , Takayuki Kitamura , Kazuki Shibanuma

Accurate evaluation of material creep behaviour is essential for the reliable operation of industrial equipment. In this study, we propose a physics-based model capable of quantitatively predicting the deformation of three-dimensional polycrystalline solids due to Coble creep. The proposed model avoids non-physical assumptions commonly adopted in conventional numerical analyses and reproduces stress-induced grain boundary diffusion—the fundamental mechanism underlying Coble creep—in a physically consistent manner. This is achieved by explicitly representing the three-dimensional grain boundary network and accounting for the interaction between stress and atomic diffusion along grain boundaries. To validate the proposed model, its numerical simulation results were compared with the theoretical equation for Coble creep deformation under uniaxial loading and with the established knowledge under multiaxial loading. The model accurately reproduces the dependence of the macroscopic creep strain rate on grain size, applied stress, and temperature, consistent with the theoretical equation. Furthermore, systematic numerical simulations were conducted to investigate the effects of polycrystalline morphology, such as grain size distribution and aspect ratio, on Coble creep deformation. The results demonstrate that variations in grain size distribution and grain aspect ratio in polycrystalline morphology can lead to measurable changes in the macroscopic creep response, even under identical loading and temperature conditions. The proposed model provides a physically grounded tool for predicting Coble creep deformation of materials under arbitrary loading conditions and polycrystalline morphologies. Moreover, it elucidates the role of microstructural factors in determining material performance, thereby advancing the understanding of GB diffusion-controlled deformation mechanisms at low stresses and over extended timescales.

材料蠕变行为的准确评估对于工业设备的可靠运行至关重要。在这项研究中，我们提出了一个基于物理的模型，能够定量预测三维多晶固体由于钴蠕变而产生的变形。该模型避免了传统数值分析中通常采用的非物理假设，并以物理一致的方式再现了应力诱导的晶界扩散-电缆蠕变的基本机制。这是通过明确地表示三维晶界网络和计算应力和沿晶界原子扩散之间的相互作用来实现的。为了验证该模型的有效性，将数值模拟结果与单轴加载下的索蠕变理论方程和多轴加载下的索蠕变理论方程进行了比较。该模型准确地再现了宏观蠕变应变率与晶粒尺寸、外加应力和温度的关系，与理论方程一致。此外，还进行了系统的数值模拟，研究了多晶形貌（如晶粒尺寸分布和纵横比）对钴蠕变的影响。结果表明，即使在相同的加载和温度条件下，晶粒尺寸分布和晶粒长径比的变化也会导致宏观蠕变响应的可测量变化。所提出的模型为预测材料在任意加载条件和多晶形态下的蠕变提供了一个物理基础工具。此外，它阐明了微观结构因素在决定材料性能中的作用，从而促进了对低应力和长时间尺度下GB扩散控制变形机制的理解。

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引用次数: 0

Strong, ductile, and hierarchical multiscale heterostructured magnesium alloy via coarse-grained twins coupled with fine-grained precipitates 通过粗晶孪晶与细晶析出相结合而形成的强、延展性和分层多尺度异质镁合金

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-02-01 Epub Date: 2026-01-06 DOI: 10.1016/j.ijplas.2026.104608

Shuaishuai Liu , Liuyong He , Tianjiao Li , Liping Zhong , Mingshuai Huo , Yongjian Wang , Wenzhen Xia , Wenhuan Chen , Wenbin Zhang , Qiyang He , Manoj Gupta , Guangsheng Huang , Bin Jiang , Fusheng Pan

Heterostructured materials provide a promising path to address the strength-ductility trade-off in Mg alloys. However, designs relying solely on grain size heterogeneity often yield limited improvements. Herein, we fabricated multiscale heterostructures in an AZ91 alloy, featuring twin-modified coarse grains and precipitate-hardened fine grains, through a combination of pre-aging, extrusion, and pre-compression treatments. The obtained material exhibits an exceptional strength-ductility combination, outperforming most existing AZ91 alloys. Mechanistic investigations reveal that this favorable combination is primarily driven by enhanced hetero-deformation induced (HDI) strengthening and hardening, which result from the accumulation of geometrically necessary dislocations (GNDs) at multiscale interfaces. Additional contributions arise from twin-matrix interactions that activate non-basal slip systems, as well as a composite strengthening effects induced by precipitates, dislocation cells, and stacking faults. The multiscale heterostructures promote uniform deformation through slip transfer, stress redistribution, and strain delocalization. Strain hardening is initially dominated by HDI effects, while traditional dislocation-mediated mechanisms become predominant at larger strain. The present approach, integrating precipitate engineering, grain size control, and crystallographic design, provides general guidelines for developing advanced lightweight materials.

异质结构材料为解决镁合金的强度-延性平衡问题提供了一条很有前途的途径。然而，仅仅依靠晶粒尺寸非均质性的设计通常只能产生有限的改进。本研究通过预时效、挤压和预压缩相结合的方法，在AZ91合金中制备了双晶改性粗晶和析出硬化细晶的多尺度异质组织。获得的材料表现出优异的强度-延展性组合，优于大多数现有的AZ91合金。力学研究表明，这种良好的组合主要是由多尺度界面上几何必要位错（GNDs）的积累所导致的异质变形诱导（HDI）强化和硬化的增强所驱动的。额外的贡献来自于激活非基底滑移系统的双基质相互作用，以及由沉淀、位错细胞和层错引起的复合强化效应。多尺度异质结构通过滑移传递、应力重分布和应变离域促进均匀变形。应变硬化最初以HDI效应为主，而传统的位错介导机制在大应变下起主导作用。目前的方法，集成了沉淀工程，粒度控制和晶体学设计，为开发先进的轻量化材料提供了一般指导方针。

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引用次数: 0

Potent interplay between L12 nanoprecipitates and 9R phase enabling strength-ductility synergy in a 650 MPa-class additively manufactured aluminum alloy L12纳米沉淀物和9R相之间的有效相互作用使650 mpa级增材制造铝合金的强度-延展性协同作用

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-02-01 Epub Date: 2025-12-20 DOI: 10.1016/j.ijplas.2025.104595

Chengzhe Yu , Xizhen Xia , Kefu Gan , Tong Wang , Peng Dong , Xiaokang Liang , Honghui Wu , Tiechui Yuan , Ruidi Li

High-strength additively manufactured (AM) Al alloy is critical for advanced lightweight applications, yet conventional strategies relying on large additions of rare-earth (RE) remain costly and sacrifice ductility. Here, we propose an alternative approach for strength-ductility synergy in a laser powder bed fusion-fabricated low-RE Al alloy, via tuning the interplay between L1₂ nano-precipitate and metastable 9R phase. This strategy is simply realized by low-power laser remelting at each building layer, followed by post-print ageing. As evidenced by computational fluid dynamics simulation and microstructural characterization, laser remelting with limited energy input reduces metallurgical defects and residual stress by refining grain microstructures and suppressing turbulent flows during solidification. Simultaneously, it promotes the in-situ formation of 9R domains through driven local Mg/Si segregation and primary L1₂ nanoprecipitates. 9R phases are stabilized when L1₂ nano-precipitates are generated adjacent during post-print ageing, establishing a unique pinning-like stabilization. The 9R domains also impede the growth and coalescence of L1₂-ordered structure. This interplay establishes a feedback mechanism: L1₂ phase inhibits the 9R-phase annihilation, while the 9R structure conversely suppresses L1₂-phase coarsening during aging. According to first-principles calculations: (i) Stacking fault energy is lowered by local Si/Mg segregation, thereby promoting the formation of stacking-faulted 9R phase, even mechanical twins during deformation; (ii) L1₂ nanoparticles thermodynamically stabilize 9R structures by inhibiting the stacking fault annihilation, prolonging their persistence under stress. This coupling mechanism between L1₂ nanoprecipitate and 9R phase enables the present alloy to have an ultrahigh yielding strength over 650 MPa with considerable deformability, predominating most of its previous counterparts.

高强度增材制造（AM）铝合金对于先进的轻量化应用至关重要，但依赖于大量添加稀土（RE）的传统策略仍然成本高昂且牺牲了延展性。在这里，我们提出了一种替代方法，通过调整L12纳米沉淀和亚稳9R相之间的相互作用，在激光粉末床熔合制备低稀土铝合金中实现强度-塑性协同作用。这一策略是通过低功率激光在每层建筑上重熔，然后进行打印后老化来实现的。计算流体动力学模拟和微观组织表征表明，有限能量输入的激光重熔通过细化晶粒组织和抑制凝固过程中的湍流，减少了冶金缺陷和残余应力。同时，它通过驱动局部Mg/Si偏析和原生L12纳米沉淀促进9R畴的原位形成。在打印后老化过程中，当L12纳米沉淀相邻产生时，9R相稳定，形成独特的钉状稳定。9R结构域也阻碍l12有序结构的生长和聚结。这种相互作用建立了一种反馈机制：L12相抑制9R相湮灭，而9R结构反过来抑制L12相在时效过程中的粗化。根据第一性原理计算：(1)局部Si/Mg偏析降低层错能，促进变形过程中形成层错相9R，甚至形成力学孪晶；（ii） L12纳米颗粒通过抑制层错湮灭，延长9R结构在应力下的持久性，从而在热力学上稳定9R结构。这种L12纳米沉淀与9R相之间的耦合机制使该合金具有650 MPa以上的超高屈服强度和相当的变形能力，优于以往的同类合金。

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引用次数: 0

Cross-slip and easy-glide CRSS in titanium: Theoretical predictions and in-situ TEM measurements 钛中的交叉滑移和易滑动CRSS：理论预测和原位TEM测量

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-02-01 Epub Date: 2026-01-02 DOI: 10.1016/j.ijplas.2025.104605

Tolga Berkay Celebi , Orcun Koray Celebi , Daegun You , Ahmed Sameer Khan Mohammed , Ashley Bucsek , Huseyin Sehitoglu

This study investigates the mechanics of prismatic and first-order pyramidal

〈 a 〉

slip in titanium (Ti), elucidating the physics of easy-glide and cross-slip through a combination of theory and experiments. Screw-character prismatic (Pr) dislocations in Ti are of particular interest because their complex cores can be stable or unstable, leading to activation by either cross-slip or planar glide. To investigate these mechanisms, site-specific micro tensile samples were prepared using focused ion beam (FIB) milling and mounted on a push-to-pull (PTP) device for in-situ transmission electron microscopy (TEM) tensile testing. The in-situ experiments provide direct observations of the onset of dislocation motion and the precise determination of the critical resolved shear stress (CRSS) for the activated mechanisms, and its evolution with load cycling. A comprehensive theory has been developed to predict the CRSS values for easy glide, cross-slip, and multiplication of dislocations. Predicted critical stresses for pyramidal (π)-to-Pr and reverse cross-slip agree closely with the experimental measurements. The latter cross-slip stress is a factor of two higher than that of unobstructed planar slip. The model accounts for overlapping dislocation cores and employs a Wigner-Seitz based cell to evaluate misfit energies. By combining ab initio density functional theory (DFT) with anisotropic elasticity, the framework identifies minimum energy pathways for dislocation glide, which can be intermittent and zig-zag. A simplified expression utilizing (π) and Pr Schmid factor ratios is proposed for critical stress corresponding to (π)-to-Pr cross-slip transition. The results are strongly dependent on crystal orientation, underscoring non-Schmid behavior. Overall, this study explores key critical stress parameters essential for informing higher-scale simulations of plasticity in Ti.

本文研究了钛（Ti）中棱柱形滑移和一阶锥体滑移的力学性质，通过理论和实验相结合的方法阐明了易滑移和交叉滑移的物理性质。钛中的螺旋形棱柱位错是特别有趣的，因为它们的复杂核心可以是稳定的或不稳定的，导致交叉滑动或平面滑动的激活。为了研究这些机制，使用聚焦离子束（FIB）铣削制备了特定部位的微拉伸样品，并将其安装在推拉（PTP）装置上进行原位透射电子显微镜（TEM）拉伸测试。原位实验提供了位错运动开始的直接观察和激活机制的临界分解剪应力（CRSS）的精确测定，以及其随载荷循环的演变。一个全面的理论已经发展到预测易滑动、交叉滑动和位错乘法的CRSS值。预测的锥体(π)- pr和反向交叉滑移的临界应力与实验结果吻合较好。后者的交叉滑移应力比无阻塞平面滑移应力高2倍。该模型考虑了重叠的位错核，并采用基于Wigner-Seitz的单元来评估错配能。该框架将密度泛函理论与各向异性弹性理论相结合，确定了位错滑动的最小能量路径，该路径可以是间歇性的，也可以是锯齿状的。利用（π）和（Pr）施密德因子比提出了（π）到（Pr）交叉滑移过渡对应的临界应力的简化表达式。结果强烈依赖于晶体取向，强调非施密德行为。总的来说，这项研究探索了关键的关键应力参数，为更高尺度的Ti塑性模拟提供了必要的信息。

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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 : 2026-01-01 Epub 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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引用次数: 0

A generalized variational framework for crack regularization: Mixed-mode fracture and crack propagation direction 裂纹正则化的广义变分框架：混合模式断裂和裂纹扩展方向

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-01-01 Epub Date: 2025-12-03 DOI: 10.1016/j.ijplas.2025.104573

Liang Xue , Jian-Ying Wu

This study proposes a generalized variational framework for mixed-mode crack regularization. It addresses two critical challenges of existing phase-field models, i.e., mis-predictions of mode-dependent fracture energy and of the crack propagation direction. For the former, a cohesive phase-field model with one single field variable and two distinct fracture energies is established for mixed-mode failure. Regarding the a priori unknown crack direction indispensable for the orthogonal energy decomposition, the criterion of minimum potential energy is derived within the generalized variational framework. Rational and robust crack paths can be predicted across a large range of material parameters and loading scenarios. Abrupt jumps in the crack direction and the resulting numerical instabilities exhibited by the criterion of maximum crack driving force are eliminated. Finally, the proposed variational framework is verified by a series of benchmark numerical examples involving complex crack propagation.

本文提出了一种广义变分框架用于混合模裂纹正则化。它解决了现有相场模型的两个关键挑战，即依赖于模式的断裂能和裂纹扩展方向的错误预测。对于混合模式破坏，建立了一个单场变量、两种不同断裂能的内聚相场模型。针对正交能量分解中不可缺少的先验未知裂纹方向，在广义变分框架下导出了最小势能准则。合理和稳健的裂纹路径可以预测在大范围的材料参数和加载场景。消除了裂纹方向上的突然跳跃和最大裂纹驱动力准则所显示的数值不稳定性。最后，通过一系列涉及复杂裂纹扩展的基准数值算例验证了所提出的变分框架。

引用次数: 0

An interface-regularized phase field model for deformation twinning 变形孪晶的界面正则相场模型

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-01-01 Epub Date: 2025-11-26 DOI: 10.1016/j.ijplas.2025.104569

Linfeng Jiang , Guisen Liu , Peipeng Jin , Yao Shen , Jian Wang

Deformation twinning, a common deformation mechanism in metals with a hexagonal close-packed (HCP) structure, produces plastic strain accompanied with the creation of twinned domains within the matrix. Phase-field models for deformation twinning often suffer from unphysically diffuse or overly wide interfaces, particularly under large and inhomogeneous driving forces. Maintaining a dynamically stable interface is essential for achieving an accurate description of interface motion. In this work, we propose a Forward-Backward Regularization (FBR) method to control the width of twin interfaces. This is accomplished by introducing an energy penalty term—linked to the gradient magnitude of the order parameter—into the total free energy functional. This method decouples the numerical control of interface width from the physical material parameters (e.g., interfacial energy), thereby preserving their intrinsic physical significance. The FBR method demonstrates robust performance in multiple scenarios, including interfacial energy-driven interface contraction, bulk driving force-induced interface expansion, and mesh size insensitivity to twin propagation. Integrated the FBR model into a coupled Crystal Plasticity Finite Element - Phase Field (CPFE-PF) model, the FBR approach is examined to effectively control interface width, reduce mesh orientation sensitivity, and reproduce twin propagation and transmission across grain boundaries. This robust, computationally efficient FBR model holds promise for broader applications in PF modeling of shear transformation bands with precise interface control.

变形孪晶是六方密排（HCP）结构金属的一种常见变形机制，它会产生塑性应变，同时在基体内产生孪晶畴。变形孪晶的相场模型经常受到非物理扩散或过宽界面的影响，特别是在大且不均匀的驱动力下。保持动态稳定的界面对于实现界面运动的准确描述至关重要。在这项工作中，我们提出了一种向前-向后正则化（FBR）方法来控制双接口的宽度。这是通过在总自由能泛函中引入与阶参数的梯度大小相关的能量惩罚项来实现的。该方法将界面宽度的数值控制与物理材料参数（如界面能）解耦，从而保留了其固有的物理意义。FBR方法在多种情况下表现出鲁棒性，包括界面能量驱动的界面收缩、大块驱动力诱导的界面膨胀以及网格尺寸对孪晶传播的不敏感。将FBR模型与晶体塑性有限元-相场（CPFE-PF）耦合模型相结合，验证了FBR方法能有效控制界面宽度，降低网格取向灵敏度，重现孪晶跨晶界传播和传输。这种鲁棒性、计算效率高的FBR模型有望在具有精确界面控制的剪切转换带的PF建模中得到更广泛的应用。

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引用次数: 0

Anisotropic compression behavior of 316 L stainless steel at room and cryogenic temperatures: The influence of twinning and transformation mechanisms 常温和低温下316L不锈钢各向异性压缩行为：孪晶和转变机制的影响

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-01-01 Epub Date: 2025-11-29 DOI: 10.1016/j.ijplas.2025.104572

Saurabh Pawar , K.U. Yazar , Khushahal Thool , Wi-Geol Seo , Chang-Gon Jeong , Yoon-Uk Heo , Shi-Hoon Choi

This study investigates the microstructural evolution and deformation behavior of 316 L stainless steel (SS) fabricated by direct energy deposition under compressive loading at room temperature (RT) and cryogenic temperature (CT), along the scanning (SD) and transverse (TD) directions. Electron backscatter diffraction, transmission electron microscopy, and electron channeling contrast imaging, combined with dislocation-based crystal plasticity simulations, were employed. The as-fabricated microstructure exhibited columnar grains with cellular substructures, and δ-ferrite at cell boundaries enriched in Cr and Mo. At RT, SD samples deformed via dislocation glide and twinning in [001]-oriented grains, gradually reorienting toward the less favorable [110] direction. TD samples predominantly deformed by slip. At CT, yield strength differed significantly between SD and TD samples, indicating mechanical anisotropy arising from grain morphology, local stress heterogeneities, and martensitic transformations (γ → ε → α′ and γ → α′). Simulations incorporating twinning- and transformation-induced plasticity (TWIP and TRIP) showed that [110]- and [111]-oriented grains relative to the loading direction exhibited higher resistance to deformation, consistent with lower twinning and martensite formation. At RT, twinning and screw dislocation glide were dominant, while at CT, anisotropy was governed by the interaction between hard and soft phases, with martensite variant selection playing a central role. The activation of TWIP and TRIP was strongly dependent on crystallographic orientation, with [001]-oriented grains showing greater deformation tendency.

研究了直接能量沉积制备的316l不锈钢（SS）在室温（RT）和低温（CT）压缩载荷下沿扫描（SD）和横向（TD）方向的组织演变和变形行为。采用电子背散射衍射、透射电子显微镜和电子通道对比成像，结合基于位错的晶体塑性模拟。制备后的微观结构表现为具有胞状亚结构的柱状晶粒和胞界富集Cr和Mo的δ-铁素体。在室温下，SD样品通过位错滑移和孪晶向[001]取向晶粒变形，逐渐向不利的[110]方向重新取向。TD样品主要由滑移引起变形。在CT下，SD和TD样品的屈服强度存在显著差异，表明晶粒形貌、局部应力非均质性和马氏体相变（γ→ε→α′和γ→α′）引起的力学各向异性。结合孪晶和相变诱导塑性（TWIP和TRIP）的模拟表明，相对于加载方向，[110]和[111]取向晶粒具有更高的变形抗力，与较低的孪晶和马氏体形成相一致。在室温下，孪晶和螺位错滑移占主导地位，而在室温下，各向异性由硬相和软相的相互作用决定，马氏体变异选择起核心作用。TWIP和TRIP的激活强烈依赖于晶体取向，[001]取向的晶粒表现出更大的变形倾向。

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引用次数: 0

Tailoring dislocation structure and constructing coherent Y2Ti2O7 and Laves stacking faults in 9Cr ODS alloys: A multiple strategy to enhance the strength and ductility 在9Cr ODS合金中调整位错结构和构建一致的Y2Ti2O7和Laves层错：提高强度和塑性的多种策略

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-01-01 Epub Date: 2025-12-05 DOI: 10.1016/j.ijplas.2025.104577

Mingsheng Yang, Jikang Li, Shengjie Dong, Zhichen Wang, Tong Liu

Simultaneously enhancing strength and ductility poses a significant challenge in 9Cr oxide dispersion strengthened (ODS) ferritic-martensitic (F-M) alloys. In this work, we propose a novel strategy combining Al-Si co-alloying with direct addition of Y₂Ti₂O₇ nanoparticles (YTO NPs), and then employing one-step quenching without tempering heat treatment to simultaneously tailor dislocation structure and construct coherent YTO NPs as well as Laves phase stacking faults (SFs) in 9Cr ODS F-M alloys. Our study reveals that adjusting Al/Si content can optimize martensite volume fraction and aspect ratio, and YTO NPs can suppress dislocation nucleation within the martensitic plane through coherent interface. This synergy mechanism improves strength-ductility via optimizing dislocation density. During deformation, besides the conventional YTO-dislocation mechanism, YTO NPs can simultaneously pin dislocations in different slip systems. Remarkably, YTO NPs can also induce the dual formation of dislocation loops and dipoles, which will inhibit the formation of axial cracks. Moreover, the precipitation of ∼100 nm Laves phases in matrix (BCC) creates deformable zones that evolve into Laves SFs, ultimately improving strength-ductility synergy. 1.5Al1Si alloy (1.5 wt% Al and 1 wt% Si) aligns with the Kocks-Mecking model, where YTO NPs and Laves SFs simultaneously enhance dislocation storage capacity (θ₀) while Laves SFs suppressing dynamic recovery (K), consequently improving work hardening rate. Finally, 1.5Al1Si alloy exhibits up to 1.2 GPa ultimate tensile strength (R_m) while maintaining 8.4 % of total extension at maximum force (A_gt). This study proposes a new strategy to enhance the strength and ductility of ODS alloys.

同时提高9Cr氧化物弥散强化（ODS）铁素体-马氏体（F-M）合金的强度和延展性是一项重大挑战。在这项工作中，我们提出了一种新的策略，将Al-Si共合金化与直接添加Y2Ti2O7纳米颗粒（YTO NPs）相结合，然后采用一步淬火而不回火热处理，同时调整9Cr ODS F-M合金的位错结构，构建一致的YTO NPs和Laves相层错（SFs）。研究表明，调整Al/Si含量可以优化马氏体体积分数和纵横比，YTO NPs可以通过共格界面抑制马氏体平面内的位错形核。这种协同机制通过优化位错密度来提高强度-塑性。在变形过程中，除了传统的YTO位错机制外，YTO NPs还可以同时在不同滑移体系中钉住位错。值得注意的是，YTO NPs还可以诱导位错环和偶极子的双重形成，从而抑制轴向裂纹的形成。此外，基体（BCC）中~ 100 nm Laves相的析出产生了可变形区，这些变形区演变成Laves SFs，最终提高了强度-延性协同作用。1.5 al1si合金（1.5 wt% Al和1 wt% Si）符合Kocks-Mecking模型，其中YTO NPs和Laves SFs同时增强了位错存储容量（θ0），而Laves SFs抑制了动态恢复(K)，从而提高了加工硬化率。最后，1.5Al1Si合金表现出高达1.2 GPa的极限抗拉强度（Rm），同时在最大力（Agt）下保持8.4%的总拉伸。本研究提出了一种提高ODS合金强度和延展性的新策略。

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引用次数: 0

Dual-scale selection of martensite variants in shape memory intermetallic compounds during thermomechanical loading 热机械加载过程中形状记忆金属间化合物马氏体变异的双尺度选择

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity

Pub Date : 2026-01-01 Epub Date: 2025-11-27 DOI: 10.1016/j.ijplas.2025.104570

Hai-Le Yan , Ying Zhao , Yudong Zhang , Weimin Gan , Claude Esling , Xiang Zhao , Liang Zuo

Generating a pre-strain by mechanical loading during martensitic transformation stands as a crucial strategy to obtain memory effect in shape memory alloys (SMAs). As martensitic transformation is realized by an anisotropic lattice deformation, the formation of martensite variants is always governed by strain accommodation. In a stress-free state, the orientation variants are organized hierarchically into colonies with a fixed number of variants. Under an external load, the transformation becomes selective. Although variant selection has long been a subject of interest, knowledge on selection via the activation of the transformation shear system under a load and by local strain mitigation is limited. Here, by a combined in-situ neutron diffraction and exhaustive EBSD crystallographic examination, the variant selection under a compressive load during martensitic transformation was thoroughly investigated using Ni₅₁Mn₃₄In₁₅ as an example alloy. Remarkably, a dual-scale selection mechanism, i.e., colony and intra-colony variants, was revealed, which is in stark contrast to the stress-free scenario. For colonies, those containing variants receiving the highest resolved shear stress on their dominant transformation shear system were selected. Within the colonies, the selection is on variant volume fraction. Those making the maximum contribution to the external compression strain were majorly selected. Nevertheless, due to local incompatible strains created by the favorable variants, the variants with deformation opposite to the external compression were also selected to mitigate local incompatible strain and promote further formation of the favorable variants. This study provides useful experimental evidence and analysis data for related crystal plasticity modeling and simulation.

形状记忆合金在马氏体相变过程中通过机械加载产生预应变是获得记忆效应的关键策略。由于马氏体相变是通过各向异性晶格变形实现的，马氏体变异体的形成总是由应变调节控制的。在无应力状态下，取向变异被分层组织成具有固定数量变异的群体。在外部负载下，转换变得有选择性。虽然变体选择长期以来一直是一个感兴趣的主题，但通过在载荷和局部应变缓解下激活转换剪切系统进行选择的知识有限。本文以Ni51Mn34In15合金为例，采用原位中子衍射和EBSD晶体学相结合的方法，研究了马氏体相变过程中压缩载荷作用下的变体选择。值得注意的是，揭示了一种双尺度选择机制，即群体和群体内变异，这与无压力情景形成鲜明对比。对于菌落，选择那些在其优势转化剪切系统中接受最高分解剪切应力的变异。在菌落内，选择是按不同的体积分数进行的。选取对外部压缩应变贡献最大的部分。然而，由于有利变异体产生的局部不相容应变，也选择了与外压缩相反变形的变异体，以减轻局部不相容应变，促进有利变异体的进一步形成。本研究为晶体塑性建模与仿真提供了有益的实验依据和分析数据。

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