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

摘要:

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。

Abstract:

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.