强变形诱导析出相回溶后的Al-Cu合金再时效行为

Re-ageing behavior of Al-Cu alloy after re-dissolution of precipitated phases caused by severe plastic deformation

采用透射电镜观察与分析,探讨含析出相的Al-Cu合金经多向压缩变形诱导析出相回溶后形成的过饱和固溶体的再时效行为。研究结果表明:Al-Cu合金由强塑性变形诱导析出相回溶形成的过饱和固溶体,在变形停止后再时效时显著加速时效析出过程;析出相的析出顺序与加热温度、变形量及变形后的晶粒尺寸有关;若加热温度足够消除强变形产生的高应力,则析出顺序为过渡相→稳定相;若加热温度不能消除变形产生的高应力,且晶粒超细化,则再析出时过渡相被抑制,直接生成稳定相。

Supersaturated solid solution was formed after re-dissolution of precipitated phases during multi-axial compression in aged Al-Cu alloy.The re-ageing behavior of strain-induced supersaturated solid solution was investigated by transmission electron microscopy.The results show that the precipitation process of the strain-induced supersaturated solid solution is significantly accelerated during re-ageing.The precipitation sequence is related to heating temperature,degree of deformation and grain size after deformation.When the heating temperature is high enough to counteract the high internal stress resulting from severe plastic deformation,the precipitation sequence is from metastable phase to stable phase;when the heating temperature is not high enough to counteract the high internal stress and the grains are ultra-refined,the precipitation sequence is that equilibrium phases are formed directly instead of metastable phases.