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通过OM、XRD、DSC、SEM和力学性能测试等手段,研究了挤压态LAZ941-0.5Y合金经不同的固溶时效处理后的组织和力学性能。结果表明:挤压态合金经固溶处理后,MgLi_2Al和AlLi相完全溶入基体,产生显著的固溶强化效果;50℃时效初期,溶质原子扩散缓慢导致析出动力不足,过饱和基体中析出短棒状的MgLi_2A过渡相,随时效时间延长,MgLi_2A相发生形貌转变,由短棒状变成点状;随时效温度的升高,溶质原子扩散速率加快,MgLi_2A相析出速率变快,部分MgLi_2A亚稳相分解为AlLi相,同时有AlLi从基体中析出。合金的峰值时效在50℃时效0.5 h时发生,随温度的升高很快发生过时效,其主要原因是AlLi软化相的出现。
The microstructure and mechanical properties of the as-extruded LAZ941-0.5Y alloy were studied by OM, XRD, DSC, SEM and mechanical testing. The results show that the MgLi 2 Al and AlLi phase completely dissolve into the matrix after solution treatment, and the solid solution strengthening effect is obvious. At the initial aging time of 50 ℃, the slow diffusion of solute atoms leads to insufficient precipitation kinetics and precipitation in the supersaturated matrix With the increase of aging temperature, the diffusion speed of solute atoms increases and the precipitation rate of MgLi_2A phase increases. Some MgLi_2A metastable phases change gradually from short rod to dot. With the increase of aging temperature, Phase decomposition into AlLi phase, while AlLi precipitation from the matrix. The peak aging of the alloys occurs at 0.5 h aging at 50 ℃. The aging of the alloys takes place rapidly with the increase of temperature. The main reason is the appearance of AlLi softening phase.