Method for making a coated Ni base superalloy article of improved microstructural stability

摘要

A coated Ni base superalloy article is provided with improved microstuctural stability under a coating at least partially diffused into an article surface portion, by avoiding the formation, after exposure to elevated temperatures, of a constituent called SRZ which can affect detrimentally mechanical properties of the article. Such avoidance results from maintaining a Re segregation factor, ReΔ, between dendrite cores and interdendritic regions of the alloy cast structure at no greater than about 40.