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通过光学显微镜(OM)、扫描电镜(SEM)和X射线衍射(XRD)研究了Mg-6Zn-xCa(x=0~1.35)合金的铸态和挤压态组织与相组成,测试了其室温力学性能。结果表明,随着Ca含量的增加,铸态组织逐渐细化,生成的Mg6Zn3Ca2相逐渐增多,而MgZn2相逐渐减少直至完全消失,第二相趋于连续网状分布于晶界处;挤压态组织明显细化,且平均晶粒尺寸从Mg-6Zn合金的15μm逐渐减至Mg-6Zn-0.47Ca合金的10μm。随着Ca含量的增加,铸态抗拉强度、屈服强度和伸长率先从Mg-6Zn合金的154MPa、67MPa、6.5%分别提高至Mg-6Zn-0.085Ca合金的230MPa、84MPa、14%,然后逐渐降低。挤压态力学性能明显提高,加入少量Ca(0.085%)后,抗拉强度和屈服强度稍降低,伸长率提高,而加入较多量Ca(0.47%)后,力学性能明显恶化。
The as-cast and as-extruded microstructures and phase compositions of Mg-6Zn-xCa (x = 0 ~ 1.35) alloys were investigated by OM, SEM and XRD. Mechanical properties. The results show that as the content of Ca increases, the as-cast microstructure gradually becomes thinner and the amount of Mg6Zn3Ca2 phase increases gradually while that of MgZn2 phase decreases until it disappears completely. The second phase tends to be continuously reticulate distributed at the grain boundary. The microstructure was significantly refined and the average grain size gradually decreased from 15 μm for the Mg-6Zn alloy to 10 μm for the Mg-6Zn-0.47Ca alloy. With the increase of Ca content, the as-cast tensile strength, yield strength and elongation increased from 154MPa, 67MPa and 6.5% of Mg-6Zn alloy to 230MPa, 84MPa and 14% of Mg-6Zn-0.085Ca alloy respectively reduce. After adding a small amount of Ca (0.085%), the tensile strength and yield strength decreased slightly, and the elongation increased. However, the mechanical properties of the composites were obviously deteriorated with the addition of more Ca (0.47%).