Thin Film Martensites

9321185 Wuttig本研究项目研究薄膜中的马氏体相变，集中于衬底上的奥氏体相变。本研究着重研究了薄膜奥氏体/马氏体/基材复合材料的弹性和滞弹性能，并用滞弹性能来表征复合材料中的冶金变化和内应力。这种方法的主要优点是，可以监测组织和微观结构的变化，粘结和应力，并研究它们对相变的影响，所有这些都是现场和同时进行的。目的是了解衬底约束和薄膜厚度的影响，以及“奥氏体”的结晶度和组织状态对相变的影响。鉴于形状记忆合金的潜在实用价值，研究了镍/钛基合金、铜基形状记忆合金、铁/锰基形状记忆合金和铁/铂/钯形状记忆合金及其杂化合金。表征技术包括X射线衍射、扫描和透射电子显微镜以及卢瑟福背散射。%%-%强调为热弹性马氏体。衬底包括具有不同缓冲层的硅，因为它具有集成微机械器件的潜力，以及正在迅速成为更重要的微机械材料之一的碳化硅。***

9321185 Wuttig This research project examines martensitic transformation in thin films, concentrating on the transformation of austenite on a substrate. This study emphasizes the elastic and anelastic properties of thin film austenite/martensite/substrate composites and use the anelastic properties to characterize the metallurgical changes in the composite as well as the internal stresses. This approach has the major advantage that the structural and microstructural changes, the adhesion and stresses can be monitored and their effect on the transformation investigated, all in-situ and simultaneously. The goal is to learn the effects of substrate constraint and film thickness, and the state of crystallinity and microstructure of the "austenite" on the transformation. In view of their potential practical importance, alloys from the four major shape memory alloy (SMA) families, nickel/titanium-based, copper- based, iron/manganese-based, and iron/platinum/palladium-based, as well as hybrids thereof, are investigated. Characterization techniques include X-ray diffraction, scanning and transmission electron microscopy, and Rutherford back scattering. %%% Emphasized are thermoelastic martensites. The substrates include silicon with different buffer layers because of the potential for micro-mechanical device integration as well as silicon-carbide which is fast becoming one of the more important micro-mechanical materials. ***