Morphological evolution of γ′ phase in K465 superalloy during thermal fatigue
(1.辽宁省沈阳市科学院金属研究所
2.北京市科学院研究生院
3.Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
4.Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016, China)
2.北京市科学院研究生院
3.Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
4.Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: 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 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.
Key words: superalloy; thermal fatigue; γ′ phase; mechanical property