Cu粉添加对Mg-6Zn-3Al合金组织和性能的影响

Effect of Cu powder addition on microstructure and properties of Mg-6Zn-3Al alloy

采用光学显微镜、扫描电镜(SEM)、能谱仪(EDS)、透射电镜(TEM)和万能拉伸试验机等研究了不同含量Cu粉添加对铸态和挤压态Mg-6Zn-3Al-xCu(x=0、0.3、0.6、0.9和1.2)合金组织和性能的影响,分析了添加Cu对合金强化机制和腐蚀性能的作用机理。结果表明:Cu粉的添加不能细化铸态Mg-6Zn-3Al合金的枝晶组织,但可抑制二次枝晶生长,使得一次枝晶粗大;添加Cu粉可使挤压态Mg-6Zn-3Al合金组织显著细化,并有MgAlCu新相生成,其依附于Mg_(32)(Al,Zn)_(49)相形成了粗大的多边形尖锐颗粒相,另有细小弥散的含Cu相存在于基体中。挤压态Mg-6Zn-3Al-0.9Cu合金的屈服强度、抗拉强度和伸长率分别为280 MPa、385 MPa和19%,腐蚀速率为1.61 g·m^(-2)·h^(-1);经固溶处理后Mg-6Zn-3Al-0.9Cu合金的力学性能略微下降,屈服强度、抗拉强度和伸长率分别为140 MPa、318 MPa和18%,但腐蚀速率增加到12.30 g·m^(-2)·h^(-1)。

Effect of different content of Cu powder addition on microstructure and properties of as cast and extruded Mg-6 Zn-3 Al-xCu(x=0,0.3,0.6,0.9,1.2) alloys was studied by means of optical microscope, scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) analysis, transmission electron microscopy(TEM) and universal tensile testing machine, and the mechanism of adding Cu on the strengthening mechanism and corrosion properties of the alloys was analyzed. The results show that the addition of Cu powder can not refine the dendrite structure of the as cast Mg-6 Zn-3 Al alloy, but can inhibit the secondary dendrite growth and make the primary dendrite coarse. The microstructure of the extruded Mg-6 Zn-3 Al alloy can be significantly refined by adding Cu powder, and a new MgAlCu phase is formed, which adheres to Mg_(32)(Al, Zn)_(49)phase to form a coarse polygonal sharp particle phase, as well as the fine dispersed Cu containing phase exists in the matrix. The yield strength, tensile strength and elongation of the extruded Mg-6 Zn-3 Al-0.9 Cu alloy are 280 MPa, 385 MPa and 19% respectively, and the corrosion rate is 1.61g·m^(-2)·h^(-1). After solution treatment, the mechanical properties of the Mg-6 Zn-3 Al-0.9 Cu alloy decreases slightly, and the yield strength, tensile strength and elongation are 140 MPa, 318 MPa and 18% respectively, but the corrosion rate increases to 12.30g·m^(-2)·h^(-1).