Morphological evolution ofγ'phase in K465 superalloy during thermal fatigue

The alternative heating/cooling cycles (thermal fatigue) of K465 superalloy were carried out. The specimens were held at 1 050℃for 300 s, then quenched into 20℃recycling water for 10 s as a cycle. During thermal fatigue,γ' precipitates changed typically from cubical to irregular shape after 10 cycles, to complex configuration after 20 cycles and raft-like shape after 30 cycles. The very fineγ' particles precipitated inter the originalγ' particles. The elastic energy dominated morphological evolution of largeγ' precipitates, and the thermal stress induced the directional growth of precipitates that minimized the total energy of the system, and the nucleation theory controlled the formation of fineγ' precipitate. The results show that the volume fraction ofγ' precipitates is increased with the increase of heating/cooling cycles, which improves the mechanical property of this alloy.

The alternative heating/cooling cycles （thermal fatigue ） of K465 superalloy were carried out. The specimens were held at 1 050 ℃ for 300 s, then quenched into 20℃ recycling water for 10 s as a cycle. During thermal fatigue, γ＇ precipitates changed typically from cubical to irregular shape aider 10 cycles, to complex configuration aider 20 cycles and raft-like shape aider 30 cycles. The very fine γ＇ particles precipitated inter the original γ＇ particles. The elastic energy dominated morphological evolution of large γ＇ precipitates, and the thermal stress induced the directional growth of precipitates that minimized the total energy of the system, and the nucleation theory controlled the formation of fine γ＇ precipitate. The results show that the volume fraction of γ＇ precipitates is increased with the increase of heating/cooling cycles, which improves the mechanical property of this alloy.