通过光学显微镜、扫描电镜等研究了浇铸温度、保温时间、稀土镧含量等工艺参数对AZ61镁合金显微组织的影响。结果表明: 随着浇铸温度的升高, 合金的组织变得均匀、晶粒变得圆整, 但也开始长大、粗化, 浇铸温度为720 ℃时, 合金的组织最均匀, 晶粒也最圆整; 保温时间的改变对合金组织影响不大; 随稀土含量的增加, 树枝状初生相α-Mg得以细化, 同时稀土相也开始长大, 当稀土质量分数为1.0%时, 合金中β-Mg17Al12相均匀分布在晶界上, 并且组织中所含的稀土相分布比较均匀, 没有出现团聚。

The effects of pouring temperature, holding time and rare earth La content on the microstructure of AZ61 magnesium alloy were investigated by OM, SEM. The results indicate that with increasing pouring temperature, the microstructure of the alloy was more uniform, grains grew up and became more rounding and coarser in the mean time. The most uniform microstructure with the most rounding grains was obtained when pouring temperature was 720 ℃. There were no obvious influences of holding time on the microstructure of the alloy. With the increase of rare earth content, dendritic primary phase of α-Mg was refined and the rare earth phase began to grow. When the rare earth content was 1.0wt.%, β-Mg17Al12 phases uniformly distributed around grain boundaries, the uniform distribution of rare earth phase was observed and no agglomeration of rare earth phase was found.