STRUCTURE OF NICRALY METAL POWDERS

Initial structure of metallic powders can be a possible source of stru ctural inhomogeneities found in plasma spray coatings. These powders p repared by rapid solidification techniques result in appropriate non-e quilibrium phases and structures. Results of structural studies perfor med by light microscopy, SEM, TEM, and EDX on NiCrAlY metallic powders are presented in this paper. The structure was found consisting of a mixture of phases including beta-NiAl, martensitic NiAl, gamma and gam ma'. Y is bound in Ni5Y yttride localized in the grain boundary region s.