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用透射电镜详细观察了含微量稀土的 Al-Zn-Mg 合金在超塑变形过程中晶界位错的形态、运动及其与晶界第二相粒子的相互作用情况。发现晶界中的第二相粒子对位错沿晶界运动有明显的阻碍作用。实验还发现在含第二相粒子较多的晶界的超塑性合金中,晶界滑动是通过位错沿晶界运动和晶界的粘滞性流动两种机制同时发生作用进行的,它们相互促进并共同推动了晶界滑动的发展。首次在透射电镜下观察到超塑变形使晶界加宽的现象,在面缩率ψ=72.2%的样品中测得某晶界的宽度约为100nm,从而证实了超塑变形的晶界滑动和晶粒转动机制。
The morphologies and motions of grain boundary dislocations and their interaction with the second-phase particles in the grain boundary during superplastic deformation were observed in detail by transmission electron microscopy. It is found that the second-phase particles in the grain boundaries have a significant hindrance to the dislocations along the grain boundaries. Experiments also found that in the superplastic alloys with grain boundaries with more second-phase particles, the grain boundary sliding occurs through the simultaneous action of dislocations along the grain boundary and the viscous flow at the grain boundaries, Promote and jointly promote the development of grain boundary sliding. For the first time, the phenomena of superplastic deformation broadening the grain boundary was observed under TEM. The width of a grain boundary was measured to be about 100 nm in a sample with a reduction ratio of ψ = 72.2%, thus confirming the grain boundary sliding And grain rotation mechanism.