熔体处理在制备Mg-9Zn-2Al镁合金半固态浆料中的作用

摘要

采用自孕育法制备新型Mg-9Zn-2Al高锌镁合金半固态浆料,研究孕育剂加入量为5％(质量分数)、导流器角度为45.时熔体处理温度对Mg-9Zn-2Al镁合金组织的影响.对孕育剂加入熔体后的熔化状况进行分析,并从原子团簇角度探讨熔体处理温度对一次孕育的作用机理.结果表明:熔体处理温度过高或过低时,组织平均晶粒尺寸较大;在695～710℃范围内,晶粒平均尺寸较小,约为47.5～48.8 μm.根据所推导出的孕育剂在导流器入口处的温度表达式,可以确定自孕育法铸造的最佳熔体处理温度,提出用固相率fs描述自孕育剂的熔化状况.%A noval high zinc-content Mg-9Zn-2Al magnesium alloy semi-solid slurry was prepared by self-inoculation method(SIM). The effect of melt treatment temperature on the microstructure was investigated when the addition of self-inoculants is 5% (mass fraction) and the angle of fluid director is 45? The melting state of the inoculants was analyzed. Furthermore, the mechanism of the primary inoculation was discussed from the standpoint of atomic cluster. The results show that the average grain size increases when the melt temperature is excessively low or high. In temperature range of 695-710 'C, the average grain size is smaller, about 47.5-48.8 urn. In SIM casting, a proper melt treatment temperature can be determined by the derived formula, which is the temperature of the inoculants in the entrance of fluid director. Meanwhile, the solid phase rations is put forward to describe the case of inoculants' melting.