微量Y、Er元素对AZ91镁合金微观组织及力学性能的影响

Effects of Y and Er Addition on Microstructure and Mechanical Properties of As-Cast AZ91 Alloy

利用SEM、XRD和EDS等手段研究了单独和复合添加微量Y、Er元素对AZ91镁合金微观组织的影响,并测试分析了合金的室温及高温力学性能。结果表明:单独和复合添加适量的Y、Er元素对AZ91镁合金微观组织都有一定程度的细化作用,连续网状分布的β-Mg17Al12相减少,复合添加对晶粒细化效果更为明显;单加Y和单加Er元素时,分别会有颗粒状Al2Y和杆状Al3Er化合物生成;复合添加时,颗粒状Al2Y中的部分Y和杆状Al3Er中的部分Er分别会被Er和Y所置换。相对于单独添加,复合添加对合金的综合力学性能的影响更为明显,随着复合添加量的增多,合金试样的抗拉强度和延伸率都呈现先增大后减小的趋势。

The microstructures of AZ91 alloy modified by yttrium and/or erbium addition were investigated by SEM,XRD and EDS.The mechanical properties of the alloys at room temperature and 150 °C were analyzed.The results show that adding Y and/or Er can sufficiently refine α-Mg grain and decrease the amount of continuous net-like β-Mg17Al12 phase.The refining effect of co-addition is more obvious than that of Y or Er addition alone.Y-Er co-addition is more efficient in improving crystal with smaller size and better mechanical properties.Part of Y in Al2Y or Er in Al3Er is substituted by Er or Y when Y and Er are co-added in AZ91 alloy.The alloy with Y-Er co-addition has better mechanical properties than that with Y or Er addition alone.With increases of RE,the tensile strength and elongation of alloys rise at first and then drop.