Effect of addition temperature on dispersion behavior and grain refinement efficiency of MgO introduced into Mg alloy

添加温度对MgO在镁合金中分散行为及晶粒细化效率的影响

The effect of addition temperature of MgO particles(MgOp)on their dispersion behavior and the efficiency of grain refinement in AZ31 Mg alloy was investigated.In addition,the grain refinement mechanism was systematically studied by microstructure characterization,thermodynamic calculation,and analysis of solidification curves.The results show that the grain size of AZ31 Mg alloy initially decreases and then increases as the MgOp addition temperature is increased from 720 to 810°C,exhibiting a minimum value of 136μm at 780°C.The improved grain refinement efficiency with increasing MgOp addition temperature can be attributed to the reduced Mg melt viscosity and enhanced wettability between MgOp and Mg melt.Furthermore,a corresponding physical model describing the solidification behavior and grain refinement mechanism was proposed.

研究MgO颗粒的添加温度对其在AZ31镁合金中的分散行为和晶粒细化效率的影响。通过组织表征、热力学计算和凝固曲线分析,系统研究晶粒细化机制。结果表明,随着MgO添加温度从720℃升高到810℃,AZ31镁合金的晶粒尺寸先减小后增大,在780℃时达到最小值136μm;随着MgO添加温度的升高,晶粒细化效率提高,这归因于Mg熔体黏度的降低以及MgO颗粒与Mg熔体之间润湿性的改善。此外,提出了描述凝固行为和晶粒细化机理的物理模型。