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本文用正电子湮没多普勒展宽S线形参数法系统研究了形变量,形变速率和形变温度对Ti-6Al-4V合金超塑形变状态下显微缺陷行为的影响。在最佳超塑形变温度和形变速率下,空位密度随应变增加而增大,位错密度未见明显变化。在最佳超塑形变温度和确定应变下,空位密度随形变速率增大而增加,但未见位错密度的明显变化。在确定的形变量和形变速度下,空位密度随温度增加而增加,位错密度则降低。在900～950℃范围的S参数值陡然下跌,这是由于此温度区间发生了动态回复与动态再结晶过程。
In this paper, the effect of deformation, deformation rate and deformation temperature on microscopic defects in Ti-6Al-4V alloy under superplastic deformation was systematically investigated by positron annihilation Doppler-spread S-line parametric method. At the best superplastic deformation temperature and deformation rate, the vacancy density increases with the increase of strain, and the dislocation density has no obvious change. At the best superplastic deformation temperature and determined strain, the vacancy density increases with the deformation rate, but no obvious change in dislocation density. At certain deformations and deformation velocities, the vacancy density increases with temperature and the dislocation density decreases. In the range of 900 ~ 950 ℃, the value of S parameter suddenly dropped due to the dynamic recovery and dynamic recrystallization process in this temperature range.