Influence of δ Phase on Hot Deformation Behavior of A Ni-based Powder Superalloy with High Nb Content

With the improvement of the thrust weight ratio of aero-engine, higher requirements are put forward for the temperature bearing capacity and performance stability of high temperature rotating parts. The strength of the common γ/γ’system superalloy decreases rapidly over 800℃, so the introduction of a more stable δ phase at high temperature was regarded as a technical route to improve the temperature bearing capacity of the material. The hot deformation behavior of a high Nb nickel-based powder superalloy containing δ phase was studied by systematic isothermal compression test and microstructure analysis. The results show that the introduction of the δ phase into the material before thermal deformation can significantly promote the recrystallization of the material, thus obtaining fine homogeneous microstructure at lower deformation temperature and higher strain rate. The pre-precipitated δ phase also hinders the inward expansion of surface micro-cracks during large deformation. The results can be used in the development of a new high-strength nickel-based powder superalloy and the forging process design.