Patent ID: 7544424

Claim:
An article comprising a substrate and a coating system on a surface of the substrate, the substrate being formed of a nickel-base alloy containing at least one refractory metal in an amount sufficient to render the substrate susceptible to a gamma/gamma-prime inversion and susceptible to forming a secondary reaction zone (SRZ) in which deleterious topologically close-packed (TCP) phases form, the coating system consisting of an aluminum-containing overlay coating and a stabilizing layer between the overlay coating and the substrate, the overlay coating containing aluminum in an amount greater by atomic percent than an amount of aluminum in the metal alloy of the substrate, the stabilizing layer consisting essentially of at least one platinum group metal chosen from the group consisting of platinum, rhodium, iridium, and palladium, wherein neither the aluminum-containing overlay coating and the stabilizing layer has undergone a diffusion treatment to diffuse the stabilizing layer and the aluminum-containing overlay coating into the substrate, and the substrate is essentially free of an SRZ that is deleterious to the mechanical properties of the metal alloy of the substrate.