Al-4.5wt%Cu合金中溶质原子及析出相对锯齿形屈服时空特性的影响

借助不同温度下的固溶处理，得到一系列具有不同溶质原子浓度及析出相含量的Al-4.5wt%Cu合金材料试件.比较这些试件在拉伸实验中的锯齿形屈服现象的时空特性，分析溶质原子与析出相对位错运动的影响，从而探究动态应变时效产生的微观机理.实验结果显示，当固溶处理温度由500℃逐步降低，应力-时间曲线上的应力锯齿跌落幅值逐渐减小，并在300℃时达到最小.继续降低固溶处理温度至100℃，应力锯齿跌落幅值又逐渐增大.同时，热处理方式的改变对剪切带的传播特性也有显著影响.实验发现，固溶处理温度高于300℃时，溶质原子对DSA的影响强于析出相；反之，固溶处理温度低于300℃时，析出相对DSA的影响强于溶质原子；室温下析出相是影响Al-4.5wt%Cu合金DSA机理的主要因素. 关键词： 铝铜合金 锯齿形屈服 动态应变时效 固溶处理

Effect of solute atoms and precipitated phase in Al-4.5wt% Cu alloys on the spatiotempopal characteristics of the serrated yielding

It is well accepted that the interaction between solute atom and precipitated phase leads to dynamic strain aging (DSA). In this research solution treatments at different temperatures are adopted to control the solute concentration in solid solution and precipitated phase content in the Al-4.5wt%Cu alloy material, and their influences on dislocation movement are analyzed by subsequent tensile experiments on these treated material specimens, and the corresponding micro-mechanism of DSA is discussed. It is found that, when the solution treatment temperature is reduced stepwise from 500℃, the amplitude of the serrated yielding decreases until it reaches a minimum at 300℃, whereas the amplitude begins to increase as the solution treatment temperature is reduced continually to 100℃. Meanwhile, the heat-treatment also affects the propagation characteristics of shear bands. The experimental results also show that, when the solution treatment temperature is higher than 300℃, the solute concentration is the key factor influencing DSA. However, when the solution treatment temperature is lower than 300℃, the intensity of DSA is determined by precipitated phase density. In the case of room temperature, the micro-mechanism of DSA is found to be primarily governed by precipitated phases.