Oxidation resistance and microstructure of Ni–Cr–Al–Y–Si coating on Ni3Al based alloy

Oxidation resistance and microstructure of Ni–Cr–Al–Y–Si coating deposited by vacuum arc deposition technique on the unidirectionally solidified Ni3Al Alloy IC6, whose typical application is in the manufacture of turbine blades and vanes of jet engines, were studied. The results of the tests show that the room temperature tensile strength and stress rupture properties at 1100°C of the alloy were not influenced by the coating, and the oxidation resistance of the alloy significantly improved. In the annealed state, limited interdiffusion of various elements was observed. After cyclic oxidation at 1100°C for 500 cycles or stress rupture at 1100°C/90 MPa for 252 h, local composition of both the coating and the base material was observed to vary continuously from the surface to the substrate due to the interdiffusion of elements between the coating and the substrate and due to the surface oxidation. The results also suggest that the Ni–Cr–Al–Y–Si coating is beneficial in improving the oxidation resistance of turbine blades and vanes made of Alloy IC6 for application in advanced jet aero-engines.