Al-Cu合金析出相在等径角挤压中的演变

Evolution of precipitates in Al-Cu alloy subjected to equal-channel angular pressing

为了研究Al-Cu合金中两种不同析出相(θ′和θ相)在ECAP变形过程中的变化.采用透射电镜(TEM)和硬度测试方法研究了析出相形貌变化以及对合金性能的影响.结果表明:在本实验中,θ′和θ相其破碎、回溶速度明显不同,两者的破碎方式也不同.θ′相先是与基体失去取向关系,随后从其内部产生位错使其破碎,而θ相是被外部基体位错所切割、破碎.θ′相与位错的相互作用方式类似于绕过机制,θ相与位错的作用方式类似于切割机制.两种状态样品的硬度在变形过程中的变化趋势相同,但在第1道次后θ相状态样品的硬度增加值高于θ′相状态.

To study the changes of two precipitates （θ＇and θ phase） in Al -Cu alloy subjected to equal-channel angular pressing （ECAP） , the morphology change and its influence on mechanical properties of the alloy were investigated by transmission electron microscopy and hardness measurement. It is shown that the speed of breaking/dissolution of θ＇phase is slower than that of θ phase. θ＇phase firstly loses the orientation relationships with matrix, then the dislocation generated from precipitates results in the refinement and dissolution of precipitates. But θ phase is sheared by external matrix dislocation. The velocity of grain refinement in θ＇phase condition is also slower than that in θ phase condition. The trend of hardness changes in these two conditions are the same, but after the first pass, the increase of hardness in θ phase condition is higher than that in θ＇ phase condition.