含Sc铝镁合金的超塑变形机制

采用透射电镜研究了含微量Ｓｃ元素的ＡｌＭｇ合金在超塑变形过程中的显微组织和位错行为。结果表明：合金在超塑变形过程中发生了四个连续过程：①动态再结晶；②晶界向晶内激发位错；③位错在晶内密集并且受到第二相Ａｌ３Ｓｃ质点的阻碍作用，同时通过攀移越过晶内弥散分布的Ａｌ３Ｓｃ粒子；④位错向晶界运动并在晶界处消失。动态再结晶是合金在超塑变形中存在的组织效应，起到了细化晶粒，诱发微细晶超塑性的作用。该合金超塑变形的主要机制为晶界滑动伴随晶内位错运动

Mechanism of Superplastic Deformation in AlMg Alloy Containing Scandium

Microstructure and dislocation behavior of the aluminium magnesium alloy containing scandium in the process of superplastic deformation were investigated by transmission electron microscope.The results show that four processes will take place in sequence during superplastic deformation, i.e., dynamic recrystallization;dislocations come from grain boundaries;motion of the dislocations within the grains is prohibited by the secondary phase Al3Sc as well as dislocations climb up and go over the dispersed particles;dislocations are annihilated in grain boundaries.It is found that dynamic recrystallization is the microstructure effect of the alloy and play a role in inducing microfine grain superplasticity during superplastic deformation. The dominant mechanism of superplastic deformation is that grain boundary sliding process will be accompanied by intergrainular dislocations.