论文标题
构建和分析表面相图，以描述Mg合金中Al和Ca的分离和溶解行为
Construction and analysis of surface phase diagrams to describe segregation and dissolution behavior of Al and Ca in Mg alloys
论文作者
论文摘要
通过考虑一组广泛的表面结构和组成，通过执行密度功能理论计算来研究与Ca和al合成的MG的分离和溶解行为。结合了从头静止的表面科学方法与有序表面结构的簇扩展，我们为这些合金构建表面相图。我们利用这些图来研究与干燥环境或与水溶液接触的表面的隔离现象和化学趋势。我们表明，水的存在极大地影响了所考虑的金属表面的稳定性和化学组成。此外，我们发现这两个合金元件的行为在质上不同：而ca在表面暴露于水中时会脱离表面并溶解，但Al显示出一种抗隔离行为，即它仍然保留在毫克的体积中。这些发现为与al/ca合金合金时，对实验观察到的腐蚀速率的增加/降低提供了解释。
Segregation and dissolution behavior of Mg alloyed with Ca and Al are studied by performing density functional theory calculations considering an extensive set of surface structures and compositions. Combining ab initio surface science approaches with cluster expansion for ordered surface structures we construct surface phase diagrams for these alloys. We utilize these diagrams to study segregation phenomena and chemical trends for surfaces in contact with a dry environment or with an aqueous electrolyte. We show that the presence of water dramatically impacts the stability and chemical composition of the considered metallic surfaces. We furthermore find that the two alloying elements behave qualitatively different: whereas Ca strongly segregates to the surface and becomes dissolved upon exposure of the surface to water, Al shows an anti-segregation behavior, i.e., it remains in Mg bulk. These findings provide an explanation for the experimentally observed increase/decrease in corrosion rates when alloying Mg with Al/Ca.
