挤压镁-镓-锌合金微观组织与力学性能

Microstructure and mechanical properties of extruded Mg-Ga-Zn alloys

镁-镓(Mg-Ga)合金是一种新型的可时效硬化型合金。在Mg-Ga合金的基础上添加少量锌(Zn),通过熔炼和热挤压,综合采用扫描电子显微镜、电子背散射衍射、透射电子显微镜、室温拉伸等表征测试手段,研究了挤压Mg-Ga-Zn合金的微观组织及力学性能。研究发现,挤压后Mg-7.6Ga wt.%和Mg-7.6Ga-1.7Zn wt.%合金具有完全再结晶组织,晶粒大小分别为51μm和38μm,表明添加Zn元素可以显著细化晶粒。通过电子背散射衍射表征,挤压态Mg-7.6Ga和Mg-7.6Ga-1.7Zn合金具有强基面织构,即[0001]α垂直于挤压方向。时效后,两种合金的硬度都明显上升。通过扫描透射电子显微分析表征,在两种合金的基体中可观察到棒状析出相,并且添加Zn可明显地增加析出相数密度。室温拉伸测试表明,挤压态Mg-7.6Ga合金的屈服强度、抗拉强度和断裂延伸率分别为118 MPa,225 MPa和25%;添加Zn后,Mg-7.6Ga-1.7Zn合金的力学性能明显提升,屈服强度、抗拉强度和断裂延伸率分别为131 MPa、250 MPa和22%。

Magnesium-gallium(Mg-Ga)alloy is a novel type of age-hardenable alloy.In this study,a small amount of zinc(Zn)was added to the Mg-Ga alloy,and the microstructure and mechanical properties of the extruded Mg-Ga-Zn alloys were characterized through scanning electron microscopy,electron backscatter diffraction,transmission electron microscopy,and room temperature tensile testing.It was found that the extruded Mg-7.6Ga(wt.%)and Mg-7.6Ga-1.7Zn(wt.%)alloys exhibit fully recrystallized microstructures,with grain sizes of 51μm and 38μm,respectively,indicating that the Zn addition can significantly refine the grains.Electron backscatter diffraction revealed a strong basal texture in the extruded Mg-7.6Ga and Mg-7.6Ga-1.7Zn alloys,i.e.,[0001]αperpendicular to the extrusion direction.The hardness of both alloys increased significantly after aging.Scanning transmission electron microscopy analysis showed the presence of rod-like precipitates in the matrix of both alloys,and the addition of Zn significantly increased the number density of precipitates.Room temperature tensile tests revealed that the yield strength,ultimate tensile strength,and elongation-to-fracture of the as-extruded Mg-7.6Ga alloy were 118 MPa,225 MPa,and 25%,respectively.After the addition of Zn,the mechanical properties of Mg-7.6Ga-1.7Zn alloy improved significantly,with yield strength,ultimate tensile strength,and elongation-to-fracture of 131 MPa,250 MPa,and 22%respectively.