High temperature oxidation resistance of an amorphous layer induced by ion implantation on the surface of Ni-based superalloy GH202

Abstract

The high-temperature cyclic oxidation behavior of Ni-based superalloy GH202 was investigated before and after Y ion implantation at 1100 °C. The chemical composition and microstructure of the alloy surface treated by ion implantation were characterized using X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, electron probe microanalysis, and scanning electron microscopy. The results showed that a 30-nm-thick amorphous layer formed on the surface of the superalloy. The collision of Y ions with the alloy atoms resulted in a large number of crystal defects, such as vacancies and dislocations. Upon increasing the implantation dose, the shock of the ions prompted the dislocations to move and form dislocation tangles and dislocation arrays, which provided short circuit diffusion channels for aluminum (Al) ions during high-temperature oxidation. The oxide film on the surface of the specimens treated by ion implantation remained intact after 40 oxidation cycles, and no internal oxidation occurred in the substrate. The Y ions provided heterogeneous nucleation particles, reduced the distance between the Al2O3 nucleation positions, and promoted the formation of continuous, dense films. The amorphous layer changed the oxidation mechanism from outward cation diffusion in the oxide films to inward anion diffusion. The growth rate of the oxide film was effectively inhabited, and the high-temperature oxidation resistance was significantly improved.