微尺度亚稳β钛合金单晶相变诱发塑性行为及其尺寸效应

项目名称： 微尺度亚稳β钛合金单晶相变诱发塑性行为及其尺寸效应

项目编号： No.51301127

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 一般工业技术

项目作者： 陈威

作者单位： 西安交通大学

项目金额： 25万元

中文摘要： 微电子元器件与微机电系统等制造技术的发展使得所用材料的外观尺度逐渐减至微纳量级。因而，有必要就该尺度材料的力学性能和微观机理展开深入研究。本项目选用Ti-10V-2Fe-3Al亚稳β钛合金单晶为模型材料，设计加工特定晶体位向的微尺度方柱试样并进行微柱体压缩实验，着重研究微尺度材料的相变诱发塑性行为及应变硬化特性。测试试样不同外观尺寸下的力学响应，确定加工硬化率、应变硬化指数等材料硬化特征参数随应变的变化规律，以及这种规律突变时对应的临界外观尺寸；观察试样变形后的微观结构特征及其随外观尺寸的演化过程，阐明应变硬化特性的微观机制和性能突变的内禀原因；探寻相变马氏体与试样外观尺寸、应变的定量关系，尝试建立微尺度材料相变诱发塑性效应的计算模型；探索试样硬化行为－微观结构特征－外观尺寸约束三者的内在关联，揭示微尺度材料应变硬化特性的物理本质。为微尺度材料力学性能评价及微器构件安全设计提供理论依据。

中文关键词： 钛合金；微尺度；力学性能；变形行为；尺寸效应

英文摘要： The geometric dimension of applied materials has been reduced to micron and nano scales due to the development of microelectronic devices and microelectromechanical systems (MEMS), but there is little known about the design rules and constitutive descriptions of these micron-scale materials. Thus, understanding their mechanical response and microstructural mechanism is necessary in order to realize the full potential applications. In this project, transformation-induced plasticity (TRIP) and strain hardening behaviors in the micron-scale materials will be systematically studied. A type of metastable β titanium alloy single crystal, i.e. Ti-10V-2Fe-3Al, will be chosen as a model material. A group of square micropillars with specific crystal orientation will be fabricated using a combined lithography and focused ion beam (FIB) micromachining technique. The microcompression testing will be carried out in an MTS Nanoindenter XP, outfitted with a flat-tip diamond punch. With these experiments, the variety curves of stress-strain as a function of sample size will be measured. The dependence of hardening parameters such as work hardening rate and strain hardening exponent on strain will be revealed. The critical sample size, below which the strain-dependent hardening trend would be broken down, will be determined. Seco

英文关键词： Titanium alloys；Micon-scale；Mechanical properties；Deformation behavior；Size effect