Unveiling the initial oxidation mechanism of a single crystal Ni-based superalloy with pre-deformation

Abstract

The role of pre-deformation on the initial oxidation mechanism of a single crystal Ni- was revealed. With pre-deformation, the recrystallized grain boundaries and dislocations provided sites for the nucleation of Al2O3 and enhanced the diffusion flux of Al irrespective of γ/γ′ interface, γ′, and γ phase. Ultimately, a thin compact α-Al2O3 layer formed, improving the oxidation resistance. Without pre-deformation, Ni and Al atoms diffused along the γ'/γ interface, however, the Al-flux is insufficient to maintain the growth of Al2O3. As a result, a loose multilayer film formed on the surface, which decreased the oxidation resistance.