NI-base superalloy having a coating system containing a stabilizing layer

摘要

A coating process and system (20) for an article (10) having a substrate (22) formed of a metal alloy that is prone to the formation of a secondary reaction zone (SRZ) (36). The coating system (20) includes an aluminum-containing overlay coating (24) and a stabilizing layer (42) between the overlay coating (24) and the substrate (22). The overlay coating (24) contains aluminum in an amount greater by atomic percent than the metal alloy of the substrate (22), such that there is a tendency for aluminum to diffuse from the overlay coating (24) into the substrate (22). The stabilizing layer (42) is predominantly or entirely formed of at least one platinum group metal (PGM), namely, platinum, rhodium, iridium, and/or palladium. The stabilizing layer (42) is sufficient to inhibit diffusion of aluminum from the overlay coating (24) into the substrate (22) so that the substrate (22) remains essentially free of an SRZ (36) that would be deleterious to the mechanical properties of the alloy.