高温长期时效对DD5单晶高温合金显微组织和持久性能的影响

摘要

研究了第二代单晶高温合金DD5在1000℃和1100℃无应力时效不同时间后的显微组织和持久性能的变化.结果表明,1000℃时效200 h后,γ'相仍呈规则立方分布,尺寸略有增加,时效500 h后,γ'相逐渐连接形筏,1000 h后,γ'相的筏状组织更加完善.1100℃相比于1000℃,γ'相长大明显,形筏程度更高.长期时效过程中均析出块状的M6C型碳化物和颗粒状的M23C6型碳化物.1000℃时效100 h及1100℃时效200 h后,μ相以针状和块状形态析出,1000℃时μ相的数量随时效时间的延长显著增加,1100℃时析出相的数量比1000℃明显减少.1000℃和1100℃时随时效温度升高和时效时间的延长,合金持久性能降低.%The microstructural evolution and stress rupture properties of the second generation single crystal superalloy DD5 after long-term aging at 1 000℃and 1 100℃without stress was investigated.The results show that γ?phase still remains regular cubic distribution after aging at 1 000℃ for 200 h,but the size of γ?phase slightly increases; the γ' phase gradually connects and rafts after long-term aging for 500 h; the rafting microstructure is more perfect after aging for 1 000 h.Compared with the microstructure at 1 000℃,the γ'phase coarsens and rafts more significantly at 1 100℃.The blocky M6C carbides and granular M23C6carbides precipitate during long-term aging.The μ phase precipitates in the form of needles and granules when aged at 1 000℃ for 100 h or at 1 100℃ for 200 h,the μ phase gradually increases with the aging time prolonging at 1 000℃.The amount of μ phase precipitated at 1 100℃ is less than that at 1 000℃.The stress rupture properties decrease with the increase of aging time and temperature at 1 000℃and 1 100℃.