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利用扫描电镜(SEM)结合能谱分析(EDS)、X射线衍射(XRD)、腐蚀失重实验、电化学极化曲线等方法,研究了0.1%,0.4%,0.7%和1.0%的Sm对AZ91D合金的微观组织和腐蚀性能的影响,并对其腐蚀机理进行分析。结果表明:随着Sm含量的增加,合金中粗大的枝状第二相(β-Mg17Al12)逐渐断裂变小,其体积分数下降,因为Sm会结合Al形成颗粒状的Al2Sm和杆状的Al3Sm,从而减少晶界处第二相的数量,使第二相呈不连续分布;AZ91D的耐腐蚀性随着Sm加入量的增多,先增加后降低;当Sm加入量为1.0%时,合金的耐腐蚀性与不添加Sm的AZ91D接近;Sm的最佳添加量为0.4%。
The effect of Sm with 0.1%, 0.4%, 0.7% and 1.0% on AZ91D was studied by scanning electron microscopy (SEM), energy dispersive X-ray diffraction (XRD), electrochemical corrosion analysis (EDS) Alloy microstructure and corrosion resistance, and its corrosion mechanism analysis. The results show that with the increase of Sm content, the coarse dendritic second phase (β-Mg17Al12) gradually breaks down and its volume fraction decreases. Because Sm combines with Al to form granular Al2Sm and rod-shaped Al3Sm, So as to reduce the number of second phase at the grain boundary, resulting in discontinuous distribution of the second phase. The corrosion resistance of AZ91D first increases and then decreases with the increase of the amount of Sm. When the amount of Sm is 1.0% The corrosiveness is close to that of AZ91D with no addition of Sm. The best addition of Sm is 0.4%.