Effects of Hot Extrusion on Microstructures and Hot Deformation Behavior of Powder Metallurgy Ni-base Superalloy PM-0002

A new powder metallurgy Ni-base superalloy PM-0002 prepared by hot isostatic pressing was treated by hot extrusion, and then the hot compression tests were conducted at the temperatures from 1 000 ℃ to 1 100 ℃ and different strain rates. The microstructures and hot deformation behaviors of the alloys before and after hot extrusion were compared and analyzed. The results show that after hot extrusion, the previous particle boundaries in the microstructure of the alloy were almost eliminated and the grains were fine equixial grains. The grain size was reduced from 11.29 μm before hot extrusion to 8.32 μm and had a relatively concentrated distribution. During the hot compression at different temperatures and strain rates, the peak stresses of the alloy after hot extrusion were slightly higher than those before hot extrusion. The deformation activity energies of the alloys before and after hot extrusion were determined as 1 012.9 and 1 146.9 kJ·mol-1 respectively.