采用扫描电镜、X射线衍射、透射电镜和硬度测试等方法,研究热暴露对不同时效态2A97铝锂合金微观组织与性能的影响。结果表明：T6和T8态合金经热暴露后物相的种类及形貌变化规律相似,随热暴露温度升高,合金中的θʹ相(Al2Cu)粗化且数量减少,T1相(Al2CuLi)向平衡相转变,合金热稳定性变差。与T8态不同的是,T6态合金中的强化相除T1相和θʹ相外,还有立方相,但该相的强化效果远低于T1相和θʹ相。立方相经200 ℃热暴露后,数量增多,经300 ℃热暴露后,回溶进入基体。故在低温热暴露后T6态合金的热稳定性优于T8态,但在高温热暴露后两种时效态合金的热稳定性基本相当。T8态合金的硬度显著高于T6态,经低温热暴露后,T8态合金的硬度下降幅度大于T6态,但两种合金高温热暴露后的硬度下降幅度基本一致。
The effects of thermal exposure on microstructure and properties of 2A97 Al-Li alloy in different aging states were studied by means of scanning electron microscope, X-ray diffraction, transmission electron microscope, and hardness test. The results show that the phase types and morphologies of T6 and T8 alloys are similar after thermal exposure. With the increase of thermal exposure temperature, θʹ phase (Al2Cu) coarsens and decreases in quantity, T1 phase (Al2CuLi) changes to equilibrium phase, and the thermal stability of the alloy deteriorates. Different from T8 alloy, the strengthening phase in T6 alloy is not only T1 and θʹ phases, but also cubic phase, but the strengthening effect of this phase is much lower than that of T1 and θʹ phases. After exposure at 200 ℃, the quantity of cubic phase increases, and after exposure at 300 ℃, it redissolves into the matrix. Therefore, the thermal stability of T6 alloy after low temperature thermal exposure is better than that of T8 alloy, but the thermal stability of the two aging state alloys after high temperature thermal exposure is basically the same. The hardness of T8 alloy is significantly higher than that of T6 alloy, and the hardness decrease of T8 alloy is greater than that of T6 after low temperature thermal exposure. However, the hardness decrease of the two alloys after high temperature thermal exposure is basically the same.
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