Pd对Ti合金钝化影响的电子理论研究

采用递归法计算了Ti合金的电子态密度、环境敏感镶嵌能、费米能级等电子结构参量.计算发现Pd在晶体体内比在其表面的环境敏感镶嵌能高，说明Pd易于在 Ti合金表面偏聚.Pd在表面时，原子团簇形成能为负值，说明Pd以团簇形式分布于合金表面.态密度计算结果表明，Pd的局域态密度局限在很窄的能量范围内(-20—-15 eV)，使Ti合金的总态密度在此区出现尖峰.该尖峰的存在降低了Ti合金的费米能级，于是表面含Pd较多的区域费米能级较低，含Pd少或不含Pd的区域费米能级较高.费米能级不同的两区域接触会形成微电池，在腐关键词：Ti合金钝化电子结构表面

The electronic theory study of the influence of Pd on the passivation of Ti alloys

The electronic structure parameters of Ti alloys, such as density of states, Fermi energy level, environment-sensitive embedding energy etc, have been calculated by recursion method. The larger environment-sensitive embedding energy of Pd in the bulk of Ti alloy than that on the surface of Ti alloy indicates that Pd is apt to segregate on the surface. The negative formation energy of Pd clusters suggests that the distribution of Pd atoms on the surface of Ti alloy is in the form of atom clusters. The range of the local density of states of Pd is narrow, while that of Ti is wide. So a peak appears in the total density of states of Ti alloys between -20 and -15 eV. This peak has a significant effect on the Fermi level. It makes the Fermi energy of the surface Ti alloys with more Pd atoms low. So the microcells form between the area with more Pd atoms and the area with fewer or without Pd atoms on the surface of Ti alloys. Ti dissolves preferentially in the corrosive media. This leads to form a layer of Pd atomic clusters on Ti alloy surface. The Pd atomic layer serves as the electrocatalytic surface, facilitating the passivation of Ti alloys and improving the corrosion resistance.