X2A66铝锂合金高温变形过程中的微观组织演变

Microstructure Evolution of X2A66 Aluminum-Lithium Alloy During High Temperature Deformation

研究了X2A66铝锂合金在高温变形过程中的微观组织及析出相的演变规律。结果表明,在变形温度为420℃,应变速率为0.01s^–1时,在变形初期,X2A66铝锂合金基体中亚晶组织不完整,同时出现少量动态再结晶晶粒;随着变形量增加,可以观察到平直且清晰的晶界,当变形量大于80%时,部分晶界内出现大量位错,在析出相周围产生位错缠结。X2A66在高温变形过程中T1相出现破碎回溶的现象,同时在变形过程中动态析出δ'相。T1相的破碎回溶使基体重新达到过饱和状态,尤其是Li元素的过饱和促进了δ'相的析出。处于晶界内部的析出相能阻碍位错运动,提升再结晶晶粒的形核率。钉扎在晶界上的析出相能有效阻碍晶界及亚晶界的运动从而降低动态再结晶速率。

The microstructure evolution of X2A66 aluminum-lithium alloy during hot deformation was analyzed.When the deformation temperature was 420°C and the strain rate was 0.01 s–1,sub-grain structure was incomplete in the matrix and a small amount of dynamic recrystallized grains were observed.When the deformation amount reached 80%,a flat and clear grain boundary and low dislocation density in the matrix can be observed.When the amount of deformation was greater than 80%,a large number of dislocations occurred in a part of the grain and impeded dislocation motion around the precipitated phase.T1 phase appeared to be broken and remelted and the δ′phase was precipitated during high temperature deformation.The crushing and remelting of the T1 phase caused the matrix to re-saturate,especially the supersaturation of the Li element,which promoted the precipitation of theδ′phase.The precipitation phase inside the grain boundary can effectively hinder the dislocation movement and increase the nucleation rate of recrystallized grains.The precipitated phase pinned on the grain boundary reduced the dynamic recrystallization rate by hindering the movement of the grain boundary and the sub-grain boundary.