定向凝固Ni3Al合金高温变形后的显微组织特征

利用金相，扫描电镜和透射电子显微镜研究了定向凝固Ｎｉ３Ａｌ合金高温变形后的显微组织特征。研究结果表明，当变形速率较快时，原始柱状晶晶界无明显变化，晶内无明显结构存在；当变形速率较慢，合金呈现塑变形时，变形初期柱状晶晶界呈现“锯齿状”，后期原始柱状晶界消失，代之以晶粒尺度约为１５ｍｍ的晶粒带，晶粒带中既有小角度晶界，也有大角度晶界。

MICROSTRUCTURE FEATURES IN DIRECTIONALLY SOLIDIFIED Ni_3Al ALLOY AFTER HIGH TEMPERATURE DEFORMATION

Optical microscopy, transmission electron microscopy and scanning electron microscopy were used to examine microstructure features of the directionally solidified Ni3Al alloy deformed under tension at high temperature. The results show that initial columnar grain boundaries have not obviously changed during the deformation under higher strain rate and there are no substructure within the columnar grains. When strain rate is lower, the initial columnar grain boundaries firstly change into sawtooth shape and then evolve into small grain belts with increasing strain during superplastic deformation. The average grain size in belt is about 15 mm containing both low angle grain boundaries and high angle grain boundaries. It is suggested thata continuous recovery and recrystallization process took place during superplastic deformation in DS Ni3Al alloy.