Mg-6Al-1Zn-Y镁合金组织及力学性能的研究

在Mg-6Al-1Zn合金的基础上添加不同质量分数的Y（分别为0％，0．5％，0．9％，1．4％），制备了4种实验合金，研究了Y的添加对合金组织性能的影响。通过X射线衍射、金相显微镜、扫描电镜、电子探针等手段分析了Mg-6Al-1Zn合金添加Y后组织结构的变化。研究结果表明，添加了不同含量Y的合金中都出现了一种新相Al2Y相。随着Y含量的增加，Al2Y相数量增多而Mg17Al 12相则减少。Y能细化合金铸态及挤压态显微组织，其细化作用在添加了0．9％Y的镁合金中尤为明显。铸态合金室温拉伸试验表明：该合金具有最佳的综合力学性能。当Y含量添加至1．4％时，Al2Y相变得粗大且出现团聚现象而导致了拉伸性能的下降。经过挤压后，合金的力学性能大幅度上升。

Microstructures and Mechanical Properties of Mg-6Al-1Zn-Y Alloys

Effects of Y on microstructures and mechanical properties of Mg-6Al-1Zn alloys containing varied contents of Y(0%,0.5%,0.9%,1.4%Y respectively) were studied.X-ray diffraction,optical microscopy,scanning electron microscopy and energy dispersive spectrum were used to analyze microstructures of the alloys.The experimental results show that alloys with variable Y contents contain a RE bearing phase Al_2Y.The amount of Al_2Y increases with Y while that of Mg_(17)Al_(12) decreases.Moreover,Y refines the microstructures of as-cast and extruded alloys.The finest average grain size is obtained in 3~# alloy with 0.9% Y with the best mechanical properties.When Y content is up to 1.4%,Al_2Y phase in 4~# alloy starts coarsening,leading to the drop of tensile strength.Properties of the studied alloys are improved significantly after extrusion.