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利用OM、XRD、SEM和EPMA等手段研究了Al-3Ti-3B细化剂对AZ31镁合金微观组织的影响。结果表明,添加适量的Al-3Ti-3B细化剂能使铸态AZ31镁合金粗大的树枝晶转变为均匀的等轴晶;加入量为0.4%时取得了较好的细化效果,固溶处理后的AZ31镁合金平均晶粒尺寸由300μm减小到50μm。TiB2和AlB2粒子的异质形核作用是促使晶粒细化的主要机制,且TiB2粒子在晶界上的偏聚可进一步阻碍晶粒长大。
The effects of Al-3Ti-3B refiner on the microstructure of AZ31 magnesium alloy were investigated by means of OM, XRD, SEM and EPMA. The results show that the coarse dendrites of the as-cast AZ31 magnesium alloy can be transformed into uniform equiaxed grains by adding appropriate amount of Al-3Ti-3B refiner. When the addition amount is 0.4%, fine densification effect is obtained. The solid solution The average grain size of the treated AZ31 magnesium alloy decreased from 300μm to 50μm. Heterogeneous nucleation of TiB2 and AlB2 particles is the main mechanism of grain refinement, and the segregation of TiB2 particles at grain boundaries can further hinder the grain growth.