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研究了SrCO_3对AZ31镁合金凝固组织的影响。结果表明:在AZ31中添加0.6%的SrCO_3,于760℃时保温10min细化效果最佳,α-Mg晶粒的尺寸由基体合金的570±15μm降至110±10μm,降幅约80.7%。通过能谱分析,结合能计算及自由能计算证实细化机理是SrCO_3反应后生成的部分Al_4C_3质点作为异质核心细化晶粒。多余的Al_4C_3质点钉扎晶界阻碍晶粒长大。Al元素随固/液界面前沿被快速推至晶界,生成沿晶界生长的β-Mg_(17)Al_(12)相,起到进一步固定晶界的作用。
The effect of SrCO 3 on the microstructure of AZ31 magnesium alloy was studied. The results show that the addition of 0.6% SrCO_3 in AZ31 and the best heat treatment at 760 ℃ for 10min have the best effect. The size of α-Mg decreases from about 570 ± 15μm to 110 ± 10μm in the base alloy, down about 80.7%. Through energy spectrum analysis, binding energy calculation and free energy calculation, it is confirmed that the refining mechanism is that part of Al_4C_3 particles generated after SrCO_3 reaction serve as heterogeneous core refinement grains. Excessive Al_4C_3 particles pinning grain boundaries hinder grain growth. The Al element rapidly pushes to the grain boundary with the front of the solid / liquid interface, and forms the β-Mg 17 Al 12 phase which grows along the grain boundary, which plays the role of further fixing the grain boundary.