采用液态淬火方法得到了Mg-6Al和Mg-6Al-0.5Zn合金固液共存界面试样,表征了溶质Al在这两种合金中的凝固偏析特征,研究了Zn对Mg-6Al合金凝固溶质偏析和凝固组织的影响。结果表明:Al元素在Mg-6Al合金中的近平衡分配系数是0.33,偏析比为2.17,最大偏析率为0.43。Zn的加入使Mg-6Al合金中溶质Al的近平衡分配系数、偏析比和偏析率都变大,导致-αMg的形态从胞状枝晶演变为等轴枝晶,合金的凝固组织得到一定程度的细化。
The solid-liquid interfaces of Mg-6Al and Mg-6Al-0.5Zn alloys were obtained by rapid quenching,the solute segregation characteristic of Al in the two alloys was analyzed.The results showed that the near equilibrium distribution coefficient,the segregation rate and the most segregation ratio for Al in Mg-6Al alloys were 0.33,2.17 and 0.43,respectively.However,when Zn was added into Mg-6Al alloys,the near equilibrium distribution coefficient,the segregation rate and the most segregation ratio for Al in Mg-6Al alloys increased.The morphology of primary α-Mg phase changed from celliform dendrite to equiaxed dendrite,and the solidification structure was refined in a way.