Mg-9Sr中间合金的组织及其对AZ31镁合金组织细化的影响

Microstructure of Mg-9Sr Master Alloys and Its Effects on Microstructure Refinement of AZ31 Magnesium Alloy

对Mg-9Sr中间合金的组织及其对AZ31镁合金组织细化的影响进行了研究。研究结果表明:常规铸态、热处理态和快速凝固态Mg-9Sr中间合金的组织均由α-Mg和Mg17Sr2相组成,但合金组织中枝晶的尺寸和Mg17Sr2相的数量和形态存在一定的差异。不同状态Mg-9Sr中间合金对AZ31镁合金均有很好的细化效果,其中热处理态Mg-9Sr中间合金的细化效果最好,其次依次是常规铸态和快速凝固态Mg-9Sr中间合金。在Sr加入量为0.1%和熔体保温时间为60min条件下,添加热处理态Mg-9Sr中间合金可使AZ31镁合金获得46μm的最小平均晶粒尺寸。

The microstructure of Mg-9Sr master alloys and its effects on microstructure refinement of AZ31 alloy were investigated. The results indicated that the microstructure of Mg-9Sr master alloys whose states are conventional casting state, heat treatment state and rapid solidification state respectively, are all composed of α-Mg and Mg17Sr2 phases. However, the dendritic sizes and the amount and morphologies of Mg17Sr2 phases are different, which could result in the different refinement efficiency to AZ31 magnesium alloys. The refinement efficiency of Mg-9Sr master alloys with heat treatment state is best, next is the Mg-9Sr master alloys with conventional casting and rapid solidification states respectively. Under the condition of 0.1% Sr adding amount and the melt holding time of 60 min, the minimum average grain size of 46um for the AZ31 magnesium alloy is obtained by adding Mg-9Sr master alloy with heat treatment state.