摘要
通过电镜观察,研究了190℃人工时效前的室温和150℃预时效对8090和2091Al-Li合金中S’(Al_2CuMg)相析出的影响。实验结果表明,自然时效后人工时效的样品中由于空位凝聚而形成空位环,S’相在这些缺陷上优先形核长大。150℃的预时效由于增加形核驱动力而促进了S’相的析出,但影响效果不如自然时效明显。高的Cu,Mg含量有利于S’相的析出。本文讨论了S’相形成的微观机理。
Effect of pre-aging at room temperature and 150℃ on the precipitation of
S' phase in 8090 and 2091 type Al-Li alloys was investigated by transmission
electron microscopy, The results indicated that in the specimens naturally aged
before aging at 190℃, S' pease was preferentially rucleated and grown on the
dislocation loops formed by vacancy condensations during natural aging, Pre-
aging at 150℃ promoted S' precipitation due to the increased driving force
for precipitation. The higher Cu and Mg contents are favourable for the S'
precipitation. The mechanism of S' precipitation was discussed.
