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Topological model of type II deformation twinning in 10M Ni-Mn-Ga
Acta Materialia ( IF 9.4 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.actamat.2020.10.020 Bibek Karki , Peter Müllner , Robert Pond
Acta Materialia ( IF 9.4 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.actamat.2020.10.020 Bibek Karki , Peter Müllner , Robert Pond
Abstract The structure of type II twins in 10M Ni-Mn-Ga is modeled using the topological method. This method predicts the same twinning parameters as the kinematic model of Bevis and Crocker. Furthermore, topological modeling provides mechanistic insight into boundary migration rates, the twinning stresses and their temperature dependence. A type II twin is envisaged to form from a precursor, which is its type I conjugate. Disconnections on the precursor k1 plane align into a tilt wall, which, after the relaxation of the rotational distortions, forms the type II boundary parallel on average to the k2 plane. The component defects may align into a sharp wall or relax by kinking into a less orderly configuration. Both interfaces can host additional glissile disconnections whose motion along a boundary produces combined migration and shear. The ease of motion of these defects increases with their core width, and this, in turn, decreases with increasing sharpness of the boundary. Some experimental evidence in other materials suggests that type II twins can reduce their interfacial energy by adopting a configuration of low-index facets, which reduces twin boundary mobility. Topological modeling suggests that such a coherently faceted structure is unlikely in 10M Ni-Mn-Ga, in agreement with the high mobility of type II twin boundaries.
中文翻译:
10M Ni-Mn-Ga中II型变形孪晶的拓扑模型
摘要 利用拓扑方法模拟了10M Ni-Mn-Ga 中II 型孪晶的结构。该方法预测与 Bevis 和 Crocker 的运动学模型相同的孪生参数。此外,拓扑建模提供了对边界迁移率、孪生应力及其温度依赖性的机械洞察。II型双胞胎被设想由前体形成,这是它的I型共轭物。前体 k1 平面上的断开排列成倾斜壁,在旋转扭曲松弛后,形成与 k2 平面平均平行的 II 型边界。组件缺陷可能会排列成尖锐的壁或通过扭结成不太有序的配置而松弛。两个接口都可以承载额外的滑动断开,其沿边界的运动会产生组合的迁移和剪切。这些缺陷的运动容易度随着其核心宽度的增加而增加,而这又随着边界锐度的增加而降低。其他材料中的一些实验证据表明,II 型孪晶可以通过采用低指数小平面的配置来降低其界面能,从而降低孪晶边界迁移率。拓扑模型表明,在 10M Ni-Mn-Ga 中不太可能出现这种连贯的刻面结构,这与 II 型孪晶边界的高迁移率一致。
更新日期:2020-12-01
中文翻译:
10M Ni-Mn-Ga中II型变形孪晶的拓扑模型
摘要 利用拓扑方法模拟了10M Ni-Mn-Ga 中II 型孪晶的结构。该方法预测与 Bevis 和 Crocker 的运动学模型相同的孪生参数。此外,拓扑建模提供了对边界迁移率、孪生应力及其温度依赖性的机械洞察。II型双胞胎被设想由前体形成,这是它的I型共轭物。前体 k1 平面上的断开排列成倾斜壁,在旋转扭曲松弛后,形成与 k2 平面平均平行的 II 型边界。组件缺陷可能会排列成尖锐的壁或通过扭结成不太有序的配置而松弛。两个接口都可以承载额外的滑动断开,其沿边界的运动会产生组合的迁移和剪切。这些缺陷的运动容易度随着其核心宽度的增加而增加,而这又随着边界锐度的增加而降低。其他材料中的一些实验证据表明,II 型孪晶可以通过采用低指数小平面的配置来降低其界面能,从而降低孪晶边界迁移率。拓扑模型表明,在 10M Ni-Mn-Ga 中不太可能出现这种连贯的刻面结构,这与 II 型孪晶边界的高迁移率一致。