Experimental Study on the Mechanism of Grain Boundary Sliding

为了阐明晶界滑移的机理，通过应力变化试验研究了晶界滑移硬化的特征。采用Bridgeman法生长了含总晶界的铝双晶。使用配有蠕变测试仪的高温显微镜。利用摄像系统测量了晶界滑移率随应力变化的变化。结果表明：(1)晶界滑移率随应力的增加而增大，无例外。然而，晶界滑移速率的增加量不仅取决于应力变化量，还取决于应力变化前的晶界滑移速率。(2)应力的降低导致晶界滑移速率的降低或滑移的停止。(3)应力降低后的再加载导致晶界滑移硬化的恢复，实验结果表明，一般晶界的晶界滑移主要是位错在晶界内的运动，位错运动受晶界周围位错结构产生的内应力的影响。

In order to elucidate the mechanism of grain boundary sliding, the characteristics of the so called grain boundary slide hardening was investigated experimentally by the stress change tests. Aluminum bicrystals containing general grain boundary were grown by the Bridgeman method. High temperature microscope equipped with creep testing instrument was used. The change in the rate of grain boundary sliding accompanied with the stress change was measured by using video recording system.The results are summarized as follows.(1) The rate of grain boundary sliding increases with the increase in stress without exceptions. However, the amount of the increase in the rate of grain boundary sliding depends not only on the amount of stress change but also on the rate of grain boundary sliding before the stress change. (2) The decrease in the stress results in the decrease in the rate of grain boundary sliding or the stop of the sliding. (3) The reloading after the stress reduction generates the recovery of grain boundary slide hardening.Based on these experimental results, it was concluded that the grain boundary sliding of general grain boundary in dominated by the motion of dislocations inside the grain boundary which is affected by the internal stresses caused by the dislocation structure around the grain boundary.