镝添加对Mg-4Y-3Nd-0.4Zr合金组织和力学性能的影响

摘要

研究了镝元素添加对Mg-4Y?3Nd?0.4Zr合金显微组织和力学性能的影响,并采用扫描电镜和透射电镜观察合金的显微组织.结果表明,铸态合金中的共晶相和方形块状Mg?RE相分别为Mg5RE相和Mg3RE17相,主要分布在晶界位置.经固溶处理后,Mg5RE共晶相溶入基体中,而Mg3RE17金属间化合物依然存在.峰时效后,添加镝元素的合金Mg?RE析出相分布更均匀,显著提高了合金的室温和高温抗拉强度,但伸长率略有下降.%Minor Dy element was added into a Mg-4Y-3Nd-0.4Zr alloy, and its effects on the microstructure and the mechanical properties at elevated temperatures were investigated. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to observe the microstructures. The results indicated that the as-cast eutectic and isolated cuboid-shaped Mg-RE phases were Mg5RE and Mg3RE17, respectively, and distributed mainly along grain boundaries. After a solution treatment, the eutectic Mg5RE phases were dissolved into the matrix, whereas the Mg3RE17 compound still remained. After peak aging, fine Mg-RE phases were precipitated homogeneously within the matrix of the alloys containing Dy. Dy addition can result in a significant improvement in the tensile strength at both room and elevated temperatures, and a slight decrease in the elongation.