The Effect of Temperature and Solute Content on the Deformation Mechanisms in Titanium Aluminides

本研究考察了钛铝化物金属间化合物合金TiAl(Gamma)和Ti3Al(Al2)在较宽的温度和应变速率范围内的塑性变形机制。确定了影响位错迁移率的因素，以便确定对塑性流动有贡献的机制。研究了位错运动的两种模型：一种研究了成键电荷密度的各向异性及其与位错运动的关系；另一种研究了非平面位错核组态对位错运动的影响。这项研究的第三部分考察了来自许多潜在滑移系统的各种位错的临界可分辨剪应力的变化。这涉及到单晶的制造，以便可以沿特定的晶体方向施加应力。实验技术包括透射式电子显微镜和高分辨率电子显微镜。这项研究增加了关于金属间化合物合金机械变形的基础知识。它关系到用于喷气发动机等高温应用的延展性强的金属间化合物合金的未来发展。

This research examines mechanisms of plastic deformation in titanium aluminide intermetallic alloys, TiAl (gamma) and Ti3Al (alpha 2), over a wide range of temperature and strain rates. Factors that influence dislocation mobilities are identified so that mechanisms that contribute to plastic flow can be determined. Two models for dislocation mobility are investigated: one looking at anisotropy of bonding charge densities and its relationship to dislocation mobility; the other at the role of non-planar dislocation core configurations on dislocation mobility. A third component of the study examines the variation in critical resolved shear stresses of various dislocations taken from a number of potential slip systems. This involves the fabrication of single crystals so that stress can be applied along specific crystallographic directions. Experimental techniques include transmission electron microscopy and high resolution electron microscopy. %%% This research adds to the fundamental knowledge concerning mechanical deformation of intermetallic alloys. It is relevant to the future development of ductile, strong intermetallic alloys for operation at high temperatures in applications such as jet engines.