TiAl 基合金超塑性变形中的位错运动

Dislocation Movement During Superplastic Deformation of Ti 33Al 3Cr 0.5Mo Alloy

研究了细晶 Ｔｉ３３ Ａｌ３ Ｃｒ０ ．５ Ｍｏ （ 质量分数） 合金在超塑性变形过程中的位错运动。透射电镜分析结果表明， 超塑性变形时， 合金中存在大量位错运动， 在晶界附近和晶粒内形成了位错网， 并在晶界上出现位错塞积。大多数位错是从晶界及α２ 相粒子处发射出来的。还发现了动态再结晶现象， 这种动态再结晶是由于位错的低可动性导致位错密度不断升高造成的。分析认为， 位错运动是 Ｔｉ Ａｌ 基合金超塑性变形过程的主要协调机理。

Abstract: The microstructure of superplastically deformed Ti 33Al 3Cr 0.5Mo (mass fraction) alloy was observed by transmission electron microscope (TEM). The observation showed a lot of dislocation pile up and nets at grain boundary, as well as in grains. Furthermore, most of the dislocations were found to originate both from grain boundaries and α 2 particles which located at grain boundaries and within gamma grains. In addition, the poor mobility of dislocations resulted in their accumulating in gamma grains, and then dynamic recrystallization occured. It is proposed that the superplastic deformation in the present TiAl based alloy is controlled by grain boundary sliding accommodated by dislocation motion and dynamic recrystallization.