Fundamental Studies on High Temperature Deformation, Recrystallization, and Grain Growth of Two-Phase Materials.

摘要

Twp - phase Materials are technologically important because optimum properties can be obtained by proper combinations of phases. Among these materials, two-phase Titanium Alloys are of particular interest for high temperature aerospace applications. To design new alloys or to optimize the properties of existing Titanium alloys, it is essential to understand the deformation behavior and microstructure evolution of alpha, alpha-beta and beta Titanium alloys which is the subject of this investigation. Another aspect of this investigation is to determine the effect of strength difference between phases on deformation behavior of two-phase materials by the Finite Element Method. It was found that the flow stress drops followed by steady state behavior observed in beta titanium alloys strongly depend on pre-strain, prior heat treatments, and amount and nature of alloying elements. The flow stress drops were attributed to the multiplication of mobile dislocations and the steady state behavior was attributed to the dynamic recovery leading to the formation of subgrains. (ttl)