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对质点强化型的高强度7475铝合金超塑变形中显微组织变化进行了研究。结果表明,在超塑变形中发生下面三个连续过程:(1)位错从晶界发出;(2)位错攀移越过晶内弥散分布的第二相质点;(3)位错消失于晶界。位错密度随应变的增加而增加。位错攀移越过弥散质点的过程是合金超塑变形的速控过程,超塑变形的主要机制是晶界滑移伴随晶内位错运动。
The microstructure changes of particle-reinforced high strength 7475 aluminum alloy during superplastic deformation were studied. The results show that the following three consecutive processes occur during superplastic deformation: (1) dislocations are emitted from the grain boundaries; (2) dislocation climbs beyond the second-phase particles interspersed within the grains; (3) dislocations disappear at Grain boundaries. Dislocation density increases with strain. The process of dislocation climbing beyond the diffusive mass point is the speed control process of the superplastic deformation of the alloy. The main mechanism of the superplastic deformation is the grain boundary sliding with the dislocation movement in the crystal.