Effect of Primary γ′ Phase on High-Temperature Endurance Performance of GH4720Li Superalloy

Abstract: To investigate the effect of the primary γ′ phase on the high-temperature endurance performance of GH4720Li superalloy, samples with different volume fractions of the primary γ′ phase were prepared by adjusting the heat treatment process. The high-temperature endurance performance was tested, and the microstructure was examined. Results indicate that samples with a higher volume fraction of the γ′ phase exhibit a greater stress rupture life. Additionally, alloy samples with varying γ′ phase volume fractions show improved plasticity and toughness at 760 °C/530 MPa. Fracture morphology results reveal that high-volume-fraction primary γ′ phase samples primarily undergo transgranular fracture, whereas low-volume-fraction samples exhibit intergranular fracture due to grain boundary sliding. During high-temperature endurance, the secondary γ′ phase in the crystal is affected. Long-term aging refines the secondary γ′ phase, resulting in a more uniform distribution. Finally, the influence of the primary γ′ phase and the creep behavior of each material group on high-temperature endurance performance are discussed.