New developments on displacive phase transformations

位移相变的新进展

基本信息

批准号：
09242103
负责人：
OTSUKA Kazuhiro
金额：
$ 58.18万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

For the five themes studied in this group, the abstracts of the results are described for each theme.(a) The mechanism of 1st order displacive transformations : The elastic constants of Ti-Ni alloy system (Ti-Ni, Ti-Ni-Cu, Ti-Ni-Fe) were measured systematically by utilizing "the parallelepiped resonance method" prior to the martensitic transformations. As a result, close relations were found to exist between the three kinds of martensitic transformations and the temperature dependence of elastic constants (c', c_<44>), and elastic anusotropy (A ≡ c_<44>/c').(b) The interaction of lattice defects with 1st order displacive transformation : The all aspects of the long-standing problem of "rubber-like behavior" was consistently explained by introducing "SC-SRO (Symmetry-Conforming Short Range Order) principle" (Nature, 1997) with respect to point defects upon displacive transformation. Furthermore, other new phenomena such as "microstructure memory" and "two-way shape memory" effects were … More found based on this principle (Phys.Rev.Lett., 2000).(c) New approach to thermodynamics of 1st order displacive transformations : For Kakeshita's theory, who treated athermal and isothermal martensitic transformations in a unified manner, systematic experiments were carried out. Thus the theory was justified by showing that an isothermal transformation will change into athermal one under magnetic field, and an athermal one into an isothermal one under hydrostatic pressure etc.(d) 1st order displacive transformations in thin films : The structures of Ti-Ni thin films produced by sputter-deposition technique were systematically studied by TEM.As a result, five precipitation states were found to exist as a function of composition and aging temperature.(e) 1st order displacive transformations in nanometer-sized alloy paricles : The martensitic transformations of nano-particles of Au-Cd and Fe-Ni alloys were observed in-situ by TEM, by using a newly developed apparatus directly connected TEM and vacuum evaporation chamber. As a result, the transformations temperatures of the alloys were found to decrease greatly, but the cause was found not to be explained by the previous theory. Less

对于本组研究的五个主题，对每个主题的结果进行了摘要描述。（a）一阶位移变换的机理：Ti-Ni合金系（Ti-Ni，Ti-Ni-Cu）的弹性常数在马氏体相变之前，利用“平行六面体共振法”对马氏体相变进行了系统的测量，结果发现三种马氏体相变与温度之间存在着密切的关系。弹性常数 (c', c_<44>) 和弹性各向异性 (A ≡ c_<44>/c') 的依赖性。(b) 晶格缺陷与一阶位移变换的相互作用：长-通过引入“SC-SRO（对称符合短程有序）原理”（Nature，1997）一致地解释了“类橡胶行为”的长期问题此外，基于这一原理还发现了其他新现象，例如“微观结构记忆”和“双向形状记忆”效应（Phys.Rev.Lett.，2000）。（c）新一阶位移变换热力学方法：对于挂下统一处理无温和等温马氏体转变的理论，进行了系统的实验，从而证明了该理论的合理性。通过证明等温转变在磁场下会转变为无热转变，以及在静水压力下等温转变会转变为等温转变。（d）薄膜中的一阶位移转变：溅射制备的Ti-Ni薄膜的结构-通过TEM系统地研究了沉积技术。结果发现，存在五种析出态，作为成分和时效温度的函数。(e)纳米尺寸合金中的一阶位移转变颗粒：使用新开发的直接连接 TEM 和真空蒸发室的装置，通过 TEM 现场观察 Au-Cd 和 Fe-Ni 合金纳米颗粒的马氏体转变，从而得出合金的转变温度。发现大大减少，但发现原因不能用以前的理论来解释。