First principles study of α_2-Ti_3Al(0001) surface and γ-TiAl(111 )/α_2-Ti_3Al(0001) interfaces

摘要

The α_2-Ti_3Al(0001) surface and γ-TiAl(111 )/α_2-Ti_3Al(0001) interfaces with six orientation relationships are studied by using the first-principle density functional theory. The calculated results indicate that the Ti_3Al(0001) surface has a higher surface energy (1.964J/m~2) and larger surface relaxations, compared with the γ-TiAl(111) surface. For the γ-TiAl(111 )/α_2-Ti_3Al(0001) interface structures, the work of separation along Ti_3Al(0001)cleavage plane is larger than that along TiAl(111) plane. In the interface region, the bonding strengths between Ti_3Al layers and between TiAl layers are smaller than those along Ti_3Al(0001) plane and TiAl(111) plane in the bulk materials, respectively. The heterogeneous interface would be the weak link in the material, and the bonding strength of interface depends on the weaker one of the two phases. The bonding characteristics of interface are analyzed by the electron local function.