直流脉冲电流对7475铝合金超塑性变形中位错运动的影响

研究了直流脉冲电流对7475铝合金超塑性拉伸时的力学性能的影响。结果表明：脉冲电流能显著提高7475铝合金的伸长率，稍微降低其变形流动应力。透射电镜观察发现晶内位错从杂乱无章的状态调整到顺电子流动的方向，各位错段相互平行排列；移动到晶界处的位错能继续以滑移-攀升的方式协调晶界处的变形。由于在超塑性变形中，晶界的变形占据主导地位，电子风在晶界处推动位错的运动，比在晶内的作用更能有效地提高7475铝合金的伸长率。

The Effect of Direct Current Pulses on the Movement of Dislocations inside 7475 Aluminum Alloy Undergoing Superplastic Deformation

The effect of direct current pulses (DCPs) on the 7475 aluminum alloy which had underwent superplastic deformation was studied. Experimental results showed that the DCPs could increase the elongation rate remarkably, whereas only decreased the flow stress slightly. TEM (Transmission Electron Microscopy) observations revealed that the morphology of intragranular dislocations was changed from the desultory state to neatly disposed parallel to each other and in accordance with the flowing direction of electrons; the dislocations reaching grain boundaries could further contribute to grain boundary deformation by so called gliding-climbing movements. Because in super-plastic deformation, the deformation taking place in intergranular regime contributed most out of the total amount of deformation, the electron wind enhanced dislocation mobility at the grain boundaries could play a more important role in improving the elongation rate of 7475 aluminum alloy.