(中南大学 材料科学与工程学院，长沙 413083)
摘 要: 采用溶剂保护方法制备了合金Mg-9Gd-4Y-0.65Mn和Mg-9Gd-4Y-0.6Zr， 并挤压成棒材。 通过光学显微镜、 X射线衍射仪、扫描电镜和透射电镜等分析研究了这两种合金铸态和变形态的显微组织和力学性能。 结果表明： 铸态含Mn合金的晶粒粗大，而含Zr合金的晶粒细得多， Zr能有效地细化Mg-RE合金的晶粒； 热变形加工使两种合金的晶粒度大大减小， 拉伸强度大幅提高， 在同等加工条件下， 含Mn合金形变细化晶粒作用更显著； 两种变形合金都有非常高的室温和300 ℃高温强度， 但含Mn合金的延伸率较高；含Zr变形镁合金适宜通过T5处理， 而含Mn变形镁合金适宜通过T6处理提高其综合拉伸力学性能。
关键字: 稀土镁合金； 显微组织； 晶粒细化； 力学性能
Mg-Gd-Y-(Mn, Zr) magnesium alloys
（School of Materials Science and Engineering,
Central South University， Changsha 410083， China）
Abstract: Mg-9Gd-4Y-0.65Mn and Mg-9Gd-4Y-0.6Zr alloys were prepared by the fluxing procedures method and then extruded into rods. The microstructures and tensile properties of the alloys both at as-cast state and at deformation state were investigated by using optical microscopy, X-ray diffractometry, scanning electron microscopy, and transmitting electron microscopy. The results show that the grains of the alloy containing Mn at as-cast state are coarser and those of the alloy containing Zr are much finer, which obviously demonstrates grain refining effect of additional element Zr on Mg-RE alloys. Hot extrusion of the two alloys can enormously decrease the grain size and increase their strength. The grain refining effect of the magnesium alloy containing Mn through extrusion will be more remarkable than that of alloy containing Zr. The two extruded magnesium alloys at room temperature and at 300 ℃ have rather high strength， furthermore, the elongation of the alloy containing Mn is higher. It is suggested that the extruded magnesium alloy containing Zr is introduced to precipitation heat treatment to T5 temper for high mechanical properties， while the extruded magnesium alloy containing Mn to T6 temper.
Key words: rare earth magnesium alloys；microstructure；grain refining； mechanical properties
