(内蒙古工业大学 材料科学与工程学院，呼和浩特 010051)
摘 要: 采用基于密度泛函理论的第一性原理方法，计算了含Ca镁合金主要第二相(Al2Ca、Mg2Ca、Mg17Al12)不同晶面的费米能级、真空能级和电子功函数和本征电势差，分析添加Ca镁合金耐腐蚀性质的电子机制。电子功函数结果表明：Mg17Al12电子功函数的平均值大于Mg基体的电子功函数，在腐蚀中Mg17Al12充当阴极相；Al2Ca电子功函数的平均值与Mg基体的电子功函数相同，在腐蚀中与基体的电子功函数相仿；Mg2Ca电子功函数的平均值小于Mg基体的电子功函数，在腐蚀中Mg2Ca充当阳极相。本征电势差结果表明：Al2Ca和Mg2Ca与Mg基体的电势差低于Mg17Al12与基体的电势差，含Ca镁合金的耐腐蚀性得到加强。
关键字: 镁合金；本征电势差；第二相；电子功函数；电偶腐蚀；第一性原理
（School of Material Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China）
Abstract:The Fermi level, vacuum level, electronic work function and the intrinsic potential difference of the main second phases (Al2Ca, Mg2Ca, Mg17Al12) of magnesium alloy with Ca contents were calculated by using the first-principles method based on density functional theory. The electronic mechanism of the corrosion resistance of Mg alloy with calcium contents was analyzed. The results of electron work function show that the mean electron work function of Mg17Al12 is larger than that of Mg matrix, and Mg17Al12 acts as cathode phase in corrosion. The mean electron work function of the Al2Ca is the same as that of the Mg matrix, which is similar to the matrix in corrosion. The average value of Mg2Ca electron work function is smaller than that of Mg matrix and acts as anode phase in corrosion. The results of intrinsic potential difference show that the potential difference between Al2Ca, Mg2Ca and Mg matrix is lower than that between Mg17Al12 and the matrix, the corrosion resistance of Mg alloy with calcium contents is strengthened.
Key words: magnesium alloy; intrinsic potential difference; second phase; electronic work function; galvanic corrosion; first-principles
