Microstructure and Corrosion Resistance of Mg-5Al-1Sr- 2Ca-XY Alloy

摘要:

研究了稀土元素Y含量的不同对Mg-5Al-1Sr-2Ca合金微观组织和耐腐蚀性的影响。使用对掺法制备了Mg-5Al-1Sr-2Ca-XY （X=0,0.5,0.7,1.0; 质量分数, %）合金。采用光学显微镜（OM）、扫描电镜（SEM）和X射线衍射（XRD）分析了该合金。结果表明，随着Y的加入，合金中出现Al2Y新相，合金晶粒得到细化。当Y含量为0.7%时，合金晶粒最细。但是当Y含量大于0.7%时，晶粒变大，并且不规则。通过静态失重测试和极化曲线法研究了合金的耐腐蚀性。发现随着Y的添加提高了合金的平衡电位和腐蚀电位，耐腐蚀性提高。在本实验范围内，当Y含量为0.7%时，合金的耐腐蚀性最好

Abstract:

The effects of different contents of Y on microstructures and corrosion resistances of Mg-5Al-1Sr-2Ca alloys were investigated. Mg-5Al-1Sr-2Ca-XY(X=0,0.5,0.7,1.0; wt%) alloys were prepared using mixture method and were analyzed by optical microscopy (OM), scanning electron microscopy(SEM) and X-ray diffraction (XRD). The results indicate that the grain size can be obviously reduced when the content of Y is 0.7 wt%. With the addition of Y, Al2Y phase is formed and acts as the heterogeneous nucleus of α-Mg to enhance the nucleation rate. Simultaneously, Al2Y is aggregated in the front of α-Mg and hinders the growth of α-Mg grains. The corrosion resistance of Mg-5Al-1Sr-2Ca-XY(X=0,0.5,0.7,1.0; wt%) alloys in 3.5% NaCl aqueous solution was investigated through static weight-loss test and polarization curve measurement. It is found that due to the addition of Y, the corrosion resistance is improved substantially. Mg-5Al-1Sr-2Ca-0.7Y alloy has a low corrosion current and the best corrosion resistance among the investigated alloys