Topological model of type II deformation twinning in NiTi martensite
Topological model of type II deformation twinning in NiTi martensite
复制标题
NiTi马氏体II型变形孪生的拓扑模型
DOI：
10.1080/14786435.2019.1587185
复制
发表时间：
2019
影响因子：
1.6
通讯作者：
K. Knowles
中科院分区：
文献类型：
--
作者：
R. Pond;J. Hirth;K. Knowles
提出了NiTi马氏体中Ⅱ型孪晶形成的拓扑模型。断开偶极子最初产生并在有理平面上扩展，随后积累形成垂直于的倾斜壁。当组成缺陷的应变和旋转畸变场在相邻晶体之间均匀分配时，就会出现平衡。所得界面平行于无理共轭面，这与经典的形变孪晶几何理论和先前发表的实验观察结果一致。有人提出，形成的II型双胞胎上发生在这种方式，而不是形成的I型双胞胎上，因为断开有有限的流动性，即使他们很容易在这个平面上成核。我们支持这一猜想表明，伯格斯矢量的缺陷有一个小的幅度，这意味着容易成核，但它们的运动沿着伴随着复杂的原子洗牌。
ABSTRACT A topological model of the formation of type II twins in NiTi martensite is presented. Disconnection dipoles are generated initially and expand on the rational plane, subsequently accumulating to form a tilt wall perpendicular to . Equilibrium occurs when the strain and rotational distortion fields of the constituent defects are equally partitioned between the adjacent crystals. The resultant interface is parallel to the irrational conjugate plane, , consistent with the classical geometric theory of deformation twinning and previously published experimental observations. It is proposed that the formation of type II twins on occurs in this manner, rather than formation of type I twins on , because the disconnections have limited mobility on even though they are readily nucleated on this plane. We support this conjecture by showing that the Burgers vector of the defects has a small magnitude, implying easy nucleation, but their motion along is accompanied by complicated atomic shuffling.