Patent ID: 6921586

Claim:
An article comprising a substrate and a coating system on a surface of the substrate, the substrate being formed of a metal alloy containing more than 3 weight percent rhenium and at least one refractory metal selected from the group consisting of tungsten, tantalum, hafnium, molybdenum, niobium, and zirconium, the coating system comprising an aluminum-containing overlay coating and a diffusion barrier coating between the overlay coating and the substrate, the diffusion barrier coating consisting of, in atomic percent, about 20% to about 90% ruthenium, about 2% to about 60% chromium, optionally up to about 50% aluminum, optionally up to about 20% of a platinum-group metal, and the balance essentially at least one of nickel, cobalt, and iron, the substrate being essentially free of a secondary reaction zone that is deleterious to the mechanical properties of the metal alloy.