高纯铝中的反常位错内耗

ANOMALOUS DISLOCATION INTERNAL FRICTION IN HIGH PURITY ALUMINIUM

本文对高纯铝的应变时效内耗行为以及所表现出的振幅效应进行研究。在一定的扭转形变以后内耗表现出反常振幅效应,这一效应在较宽的温区都可观察到,但在完全退火或拉伸形变的试样中不出现。扭转形变的方式对振幅效应有影响。纯度越低,越不易观察到这一效应。本文认为反常振幅效应的出现归因于形变导致位错密度过高,位错可动的范围较小,从而消耗的能量不再随应力显著增大。室温下时效内耗的增大可能是形变引入的空位帮助位错滑移所引起的。

The behavior of internal friction during strain ageing and amplitude-dependent effect behaved in high purity aluminium were studied. After specimen is twisted to a certain degree, internal friction exhibits anomalously amplitude dependent effect. This can be observed in a large temperature region but does not appear in completely annealed or elongated specimens. The way of twisting deformation of specimen can affect amplitude-dependent effect. As the purity is lower, the anomalously amplitude-dependent effect is not so easy to be observed. It is considered that the appearance of anomalously amplitude-dependent effect is attributed to the reason that deformation leads to high enough dislocation density and much smaller region allowed for the movement of dislocations. The increase of nternal friction during strain ageing at room temperature is suggested to be due to the dislocation slip aided by vacancy produced through deformation.