Abstract:The microstructure and creep mechanisms of FGH95 nickel-base superalloy were investigated by full heat treatment, microstructure observation, lattice parameters determination and creep curves. Results show that after the alloy is HIP treated, coarse g ￠ phase discontinuously distribute along the previous particle boundaries. After solution treatment at high temperature and twice aging, the grain size has no obvious change, and the amount of coarse g ￠ phase decreases. Moreover, the fine g ￠ phase and MC carbides dispersedly precipitate in the grain, which can enhance the creep resistance of the alloy. Because the formation elements of g ￠ phase (Al and Ti) are dissolved into the g matrix, the lattice parameter of g ￠ phase increases while the g phase decreases at the same time by XRD spectral line measurement, which results in the lattice misfit of g/g ￠ phases decreasing. In the ranges of experimental temperatures and applied stresses, the creep activation energy is about 630.4 kJ/mol. During creep, the mechanisms of FGH95 alloy are dislocation moving in the matrix or shearing into the g ￠ phase. Thereinto, the creep dislocations move over the g ￠ phase by Orowan mechanism; however, the <110> super-dislocation shearing into the g ￠ phase is decomposed to form the configuration of (1/3)<112> super-Shockleys partials plus the stacking fault.