Crystallography of Martensitic Transformations and Type II Twinning

马氏体相变和 II 型孪晶的晶体学

基本信息

批准号：
61550477
负责人：
OTSUKA Kazuhiro
金额：
$ 1.34万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

The phenomenological crystallographic theory of martensitic transformations is well established. But, a perfect agreement between theory and experiment for a complete set of crystallographic parameters is rather rare, except for a {3,10,15}}transformation in fe-pt, fe-mn-c and fFe-Pt, Fe-Mn-C and Fe-Al-Cical" case in au-47,5at%cd alloy. Ane a.pectCin improvOng the agreement is to find out a correct lattice invariant shear. previously, twinningPmode as a lattice invariant shear was believed to be type i, whose twin pTane Iriginates from a mirror plane in the parent phase. but, type ii twinninB, whType IInning direction originates from a two-fold symmetry direction in the parent phase, is also geometrically possible. in the present invesIigation, we found that the theory perfectly applies to the beta_1 gamma<@21<@D21@>D2sforma<@D21@>D2 cu-al-ni alloy by inCu-Al-Nng<111>gamma: type ing<111>gamma; Type II twinning for all crystallographic parameters simultaneously measured. This is an alloy where theory and experiment were inconsistent previously. Similarly, we found that the lattice invariant shears in Ti-Ni and Cu-Sn alloys were Type II twinning, and that consistent agreements were obtained between theory and experiment for these alloys. However, in Au-Cd and Ag-Cd alloys, the lattice invariant shear were found to be type I twinning as previously reported. Thus, we found that both Type I and Type II twinning are present as lattice invariant shears, dependent upon alloy systems. Further-more, we found that we can get a good agreement between theory and experiment, if we choose a lattice invariant shear correctly from the phenomenological crystallographic theory.

马氏体转变的唯象晶体学理论已经很成熟。但是，除了 fe-pt、fe-mn-c 和 fFe-Pt、Fe-Mn 中的 {3,10,15}} 转变之外，理论与实验之间对于一整套晶体学参数的完美一致是相当罕见的。 au-47,5at%cd 合金中的“-C 和 Fe-Al-Cical”情况。改进协议的一个目的是找出正确的晶格不变剪切。之前，孪生 P 模式作为晶格不变剪切被认为是i型，其孪晶pTane源自母相的镜面，但是，ii型孪生B，whType IInning方向源自母相的二重对称方向，在几何上也是可能的。在目前的研究中，我们发现该理论完全适用于 beta_1 gamma<@21<@D21@>D2sforma<@D21@>D2 inCu-Al-Nng<111>gamma 的 cu-al-ni 合金：ing<111>gamma 型；同时测量的所有晶体学参数的 II 型孪生类似地，我们发现以前的理论和实验不一致。 Ti-Ni 和 Cu-Sn 合金中的晶格不变剪切为 II 型孪晶，并且这些合金的理论与实验得到了一致的一致性。然而，在 Au-Cd 和 Ag-Cd 合金中，晶格不变剪切被发现为 I 型孪生，如先前报道的。因此，我们发现 I 型和 II 型孪生都以晶格不变剪切的形式存在，具体取决于合金系统。此外，我们发现，如果我们从唯象晶体学理论中正确选择晶格不变剪切，我们可以在理论和实验之间获得良好的一致性。