Deformation twinning plays an important role in enhancing the mechanical properties of metals and alloys by mechanisms such as twinning-induced plasticity and strain hardening. However, internal stress concentration associated with the interactions and reactions of twins may also lead to the degradation of ductility and fracture toughness. While the elastic behavior of individual twin types has been extensively studied, the crystallographic reactions among multiple types of twins have not been well recognized, which could produce high-index or irrational twins as well as byproduct disclinations. A theoretical framework to predict twin-twin reaction products and quantify associated internal stress is still unavailable. Here we suggest a general approach to investigate twin-twin reactions through symmetry-dictated characteristic defect analyses and stress field calculations based on disclination theory. By using Mg as an example, a systematic study of multiple types of twin-twin reactions has been conducted. The product defects arising from the reactions and associated internal stress fields have been determined analytically, which are validated by numerical simulations and experimental measurements. This work not only establishes a theoretical foundation for quantifying defect-induced internal stress concentration from complicated twin-twin interactions/reactions, but also offers new insights into the impact of deformation twins on mechanical properties.

中文翻译：

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Mg 合金中与多种类型的孪晶反应相关的离散化诱导内应力的系统研究：解析解和数值计算


变形孪晶通过孪晶诱导塑性和应变硬化等机制在增强金属和合金的机械性能方面发挥着重要作用。然而，与孪生体相互作用和反应相关的内应力集中也可能导致延展性和断裂韧性的下降。虽然已经广泛研究了单个孪晶类型的弹性行为，但多种类型双胞胎之间的晶体学反应尚未得到很好的认识，这可能导致高折射率或不合理的孪晶以及副产物倾斜。预测双胞胎反应产物和量化相关内应力的理论框架仍然不可用。在这里，我们提出了一种通过对称性决定的特征缺陷分析和基于离散度理论的应力场计算来研究孪生-孪生反应的通用方法。以 Mg 为例，对多种类型的双胞胎-双胞胎反应进行了系统研究。反应和相关内应力场产生的产品缺陷已通过分析确定，并通过数值模拟和实验测量得到验证。这项工作不仅为量化复杂的孪生孪生相互作用/反应引起的缺陷诱导的内应力集中奠定了理论基础，而且还为变形孪生对机械性能的影响提供了新的见解。