Al-Cu合金应力时效的动力学研究

对Al-Cu合金分别进行不同的单级和“双级”应力时效处理,结合电阻率测量和透射电子显微镜两种手段,研究了外加应力对于片状析出物析出动力学和择优取向效应的影响。结果表明:在较低温度下时效,相对电阻率在时效初期时出现了较小的上升,说明外加应力对Al-Cu合金的片状GP区有促进作用。在较高温度下时效,相对电阻率没有出现上升阶段,但其下降幅度明显降低,说明外加应力对θ″相的析出动力学也有影响。不同温度下的“双级”时效处理结果表明:外加应力对时效初期择优取向的影响作用要强于对时效后期择优取向的。用扩散理论证明:在共格片状相析出时,扩散系数呈现出明显的各向异性,从而形成了观察到的择优取向效应。

Kinetics Study on Stress Aging of Al-Cu Alloy

Different kinds of stress aging processes were used for Al-Cu alloy. With the determination of resistivity and the observation by transmission electronic microscope (TEM), the effect of external stress on the kinetics of precipitation and the stress-orienting effect were investigated. It can be concluded that the external stress has effect on the kinetics of coherent zone with disc shape, both the GP zone and the double prime theta phase. With the treatment of two-step stress ageing process, it can be seen that the external stress has a stronger effect on the early stage of ageing independent of ageing temperatures. Using the theory of diffusion, a semi-quantitative explanation to the preferentially orienting effect was given.