Dislocation configuration in DZ125 Ni-based superalloy after high temperature stress rupture

The influence of the melt superheating treatment on the dislocation configuration in the as-cast and heat-treated samples of DZ125 Ni-based superalloy after high temperature stress rupture is studied. The results show that with the increase of the melt superheating temperature, the stress rupture life of the as-cast sample is increased and that of the heat-treated sample is first increased and then reduced. When the superheating temperature is 1650°C, the stress rupture life of the heat-treated sample reaches the maximum. With the increase of the melt superheating temperature, the dislocation density is increased and the waved or irregular dislocation networks appear in the as-cast sample, while the regular polygonal dislocation networks appear in the heat-treated sample, which is helpful to elevate the stress rupture property. The Burgers vectors of dislocations in the network are respectively a/2<110> and a<100>. The high temperature stress rupture deformation mechanism is mainly shearing and climbing of dislocation. It is demonstrated that there are few dislocations shearing the γ' phase and there are dislocation arrays or pairs climbing over the γ' phase.