Microstructure in the cubic to monoclinic transitionin the technologically important Ti-Ni shape memory alloys isconsidered. Using a geometrically nonlinear theory ofmartensitic transformations, the twinned martensite,austenite-martensiic, wedge, triangle, and diamondmicrostructures arc studied. Specifically, compound, type I, andtype II twins are possible for any choice of the lattice parameters;while, non-standard twins may exist with special latticeparameters only. In addition, 192 habit planes are found for aparticular Ti-Ni alloy, but only 24 have been unambiguouslyobserved in experiments. Further, the twinned wedge is possiblein this alloy, but the triangle and diamond are not. These latterthree are special microstructures, which provide a mechanismthrough which a specimen can easily transform and are possibleonly for alloys with specific lattice parameters. A completeenumeration of the various microstructures is given, andalgorithms are presented so that the calculations can be repeatedwith different lattice parameters.
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机译：考虑了技术上重要的Ti-Ni形状记忆合金中立方晶系到单斜晶系转变的微观组织。利用几何非线性的马氏体相变理论，研究了孪生马氏体、奥氏体-马氏体、楔形、三角形和金刚石微观结构的弧形。具体来说，复合、I 型和 II 型孪晶可用于任何晶格参数的选择;而非标准孪生体可能仅存在具有特殊晶格参数。此外，还发现了192个特定的Ti-Ni合金的习惯平面，但在实验中只有24个被明确观察到。此外，在这种合金中可以形成孪生楔形，但三角形和金刚石则不然。后三种是特殊的微观结构，它们提供了一种机制，通过该机制，试样可以很容易地转变，并且仅适用于具有特定晶格参数的合金。给出了各种微观结构的完整枚举，并给出了算法，以便可以使用不同的晶格参数重复计算。
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