Oxygen Atoms In The Metal Of Zr (0001) Near The Surface And Tial (111) Surface Diffusion,

Oxidation of metal and intermetallic compounds is always a problem on which people concentrate, for it is relative to the mechanical and corrosion properties of materials. Basing on the density functional theory (DFT), we used Nudged Elastic Band (NEB) method to study the diffusion of oxygen atom on TiAl(111) and Zr(0001) surfaces. So that we can understand further the physical mechanism of earlier oxidation of metal surfaces.In this paper, the status of research on the oxidation of metal Zr and intermetallic compound TiAl is first presented. Secondly, the study methods DFT and NEB are introduced. And then the calculated minimum energy path (MEP) and activation energy of oxygen atoms diffusing on TiAl(111) and Zr(0001) surfaces are given. The calculated results indicate that: First, the activation energy of diffusion is 0.77eV when oxygen atom diffuses on the Zr(0001) surface, i.e. it diffuses from the most stable position (the surface face-centered cubic (SFCC) site) to the metastable position (the surface hexagonal close-packed (SHCP) site); Second, when oxygen atom diffusing into the Zr(0001) surface, it diffuses from the most stable position SFCC to the metastable position (the octahedral interstice between the first and second atomic layer noted by Octa(1,2)), and then to the octahedral interstice between the second and third atomic layer noted by Octa(2,3). In this process oxygen atom need to overcome two energy barriers. The activation energy of them are 2.14eV and 2.57eV, respectively. Third, the diffusion of oxygen atoms on the Zr(0001) surface is easier than the diffusion into the Zr(0001) surface. And last, when oxygen atom diffuses into the TiAl(111) surface, it diffuse from the most stable position SFCC, which is above the Al atom in third layer, (noted by SFCC-Al) to the position of the octahedral interstice between the first and second atomic layer (Octa(1,2)) under it, and it's activation energy of diffusion is 2.91eV which is higher than the diffusion of oxygen atom on the Zr(0001) surface.