Grain Growth Kinetics and ?' Dissolution Behavior of a Novel Disc Superalloy GH4065A

A series of heat treatments with varying temperatures and holding times have been performed on a nickel-based disc superalloy, GH4065A. It is shown that, at the sub-solvus temperature, the grain size remained unchanged while the primary & gamma;& PRIME; particles dissolved slowly and finally stopped decreasing. At super-solvus temperatures, however, rapid grain growth occurred within 60 min, and the & gamma;& PRIME; particles significantly decreased until fully dissolved. The & gamma;& PRIME; dissolution kinetics equation and grain growth kinetics equation of GH4065A have been established through the development of models, which could be used to forecast the grain size and & gamma;& PRIME; volume fraction at different temperatures for a certain time. Moreover, it was found that the primary & gamma;& PRIME; particles showed significant pinning effects on the grain boundary migration. The dissolution of & gamma;& PRIME; particles accounts for the rapid grain growth at the super-solvus temperature. This study provides a theoretical basis for precise control of the microstructure of advanced disc superalloys through heat treatment.