从“结晶游离”的角度研究了Al、Zn元素对镁合金晶粒的细化机理,建立了一类可用于评估“游离晶”对合金组织细化能力的数学模型。分析结果表明,Mg-Al合金中的游离晶对合金组织的细化能力高于相同溶质浓度的Mg-Zn合金,并且溶质浓度越高,游离晶的细化能力差别越大,这可能是导致相同浓度的Mg-Al合金晶粒尺寸更加细小的主要原因。 From the perspective of “free crystallization”, the grain refinement mechanism of Al and Zn elements on magnesium alloy was studied and a mathematical model was established to evaluate the refinement ability of “free crystal” alloy microstructure. The results show that the refinement ability of free crystals in Mg-Al alloy is higher than that of Mg-Zn alloy with the same solute concentration, and the higher the solute concentration, the greater the difference in the refining ability of free crystals may be, The main reason for the finer grain size of the same concentration of Mg-Al alloy.