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通过光学显微镜和扫描电子显微镜研究了Mg-6Zn-x Gd(x=0~4)合金的挤压态组织,测试了其拉伸力学性能和耐蚀性能。结果表明:随着Gd含量的增加,挤压态组织明显细化,平均晶粒尺寸从Mg-6Zn合金的12mm逐渐减至Mg-6Zn-3.41Gd合金的2mm;挤压态拉伸力学性能明显提高,抗拉强度σ_b和屈服强度σ_(0.2)分别逐渐提高至Mg-6Zn-3.41Gd合金的350 MPa和325 MPa,延伸率δ先降低后提高,且均不低于10%。挤压态Mg-6Zn合金的腐蚀速率较慢,为典型的局部腐蚀;添加少量Gd(质量分数0.66%)后,合金的腐蚀速率稍增大,但腐蚀变得更均匀,朝着均匀腐蚀的方式发展;添加较多量Gd(1.66%和3.41%)后,合金的耐蚀性能急剧恶化。
The microstructure of Mg-6Zn-xGd (x = 0 ~ 4) alloy was studied by optical microscope and scanning electron microscope. The tensile mechanical properties and corrosion resistance of the alloy were tested. The results show that with the increase of Gd content, the microstructure of the extruded state is obviously refined and the average grain size decreases from 12mm of Mg-6Zn alloy to 2mm of Mg-6Zn-3.41Gd alloy. The mechanical properties of extruded state are obvious The tensile strength σ_b and yield strength σ 0.2 gradually increase to 350 MPa and 325 MPa respectively for Mg-6Zn-3.41Gd alloy. The elongation δ decreases first and then increases, and both are not less than 10%. The corrosion rate of the as-extruded Mg-6Zn alloy is relatively slow, which is a typical local corrosion. After a small amount of Gd (mass fraction 0.66%) is added, the corrosion rate of Mg-6Zn alloy slightly increases but the corrosion becomes more uniform towards the uniform corrosion The corrosion resistance of the alloy was drastically deteriorated after adding a large amount of Gd (1.66% and 3.41%).