The evolution history of superalloy powders during hot consolidation and powders plastic deformation

Powder metallurgy superalloys are widely used to produce critical rotating parts in turbine engines. However, the issues like what is the driving force of precipitation on prior particle boundary (PPB) during consolidation and how the PPB structure evolves during plastic deformation still remain to be resolved. In this study, with the characterization of the microstructure evolution from powder, consolidation, to plastic deformation, the segregation of alloying elements on the particle boundaries at elevated temperature was analyzed by equilibrium thermodynamic calculations, and the distortion of PPB structure under large plastic deformation was quantitively simulated by finite element (FE) methods. The results indicated that surface energy serves as the main driving force of PPB precipitation and hot extrusion could distort the PPB structure and yield more uniformly refined grains.