In, after the hot disclosing in the midst of the alloy microstructure of the product

摘要

PROBLEM TO BE SOLVED: To provide a coated Ni base superalloy product improved in the stability of the microstructure under coating. ;SOLUTION: In the microstructure of an alloy in the surface part of the product under coating at least partially diffused over the surface part of the product, the harmful formation of secondary reaction zones(SRZ) after its exposure to a high temp. is evaded. The evasion of the formation of SRZ can be attained by neutralizing stress in the surface part in such a manner that, prior to the coating, the stress parts are physically removed or the stress parts are recrystallized into a fine-grained structure, and after that, the fine-grained structure is consumed by the diffusion of elements in a coating method. Furthermore, the formation of SRZ can be evaded also by regulating the Re segregation coefficient {ReΔ} between the dendrite core and the region between dendrite crystals in the alloy cast structure to about ≤40.;COPYRIGHT: (C)1997,JPO