Morphological Evolution of Carbides in DZ125 Superalloy during Heat Treatment
Morphological evolution of carbides in DZ125 superalloy during heat treatment was investigated by using SEM and EDS. The results show that in DZ125 directionally solidified superalloy, the MC carbide is either smooth platelet or bone-shaped structure with nodes in morphology in as-cast state, which is rich in Ta, Ti and Hf. During solid solution treatment, parts of primary MC carbides dissolve, so that the morphology of MC carbide changes from smooth and regular surface to scattered configuration. During aging heat treatment and long term aging, the secondary MC carbides enriched in Hf element precipitated from the matrix. Moreover, there is some M6C carbide enriched in W element precipitated on the grain boundary. With the process of heat treatment, the content of Hf element in MC carbides increases obviously.