Method for the protection of a hafnium-free, nickel-based monocrystalline superalloy part against corrosion and oxidation

A process for protecting a hafnium-free nickel-based single-crystal superalloy part against corrosion and oxidation, wherein the process comprises at least the following steps consisting in:

• manufacturing a hafnium-free nickel-based single-crystal superalloy part,
• depositing, on said part, a first layer comprising hafnium, then an undercoat of an alloy comprising at least 10 atomic % aluminium and a second layer comprising hafnium, simultaneously or alternately, so as to form a mixed layer, and finally a third layer comprising hafnium,
• diffusing said first layer comprising hafnium, so as to form a first interdiffusion zone in the upper part of said hafnium-free nickel-based single-crystal superalloy part, and diffusing the third layer comprising hafnium, so as to form a second interdiffusion zone on the surface of said mixed layer,
• after the diffusion treatment, carrying out an oxidation treatment of said second interdiffusion zone, so as to obtain a layer of hafnium-doped alumina on the surface of said second interdiffusion zone.