一种6Re/3Ru镍基单晶高温合金微观组织的稳定性和高温持久性能

Microstructural Stability and Stress Rupture Property of a 6Re/3Ru Containing Nickel-based Single Crystal Superalloy

用场发射扫描电镜(FE-SEM)和透射电镜(TEM)观察一种第四代镍基单晶高温合金长期时效和持久断裂后的微观组织和位错组态,研究了这种合金在1000℃和1130℃长期时效过程中的组织演化和在1100℃/140 MPa条件下的持久性能。结果表明:这种合金具有较好的组织稳定性,在1000℃长期时效过程中γ’相逐渐长大,但是在1000 h后仍有较好的立方度且没有TCP相析出。在1130℃长期时效500 h后γ’相发生连接和筏化;时效200 h后开始析出TCP相,时效1000 h后合金中TCP相的面积分数只有0.04%。在1130℃长期时效500 h后,γ/γ’界面形成位错网并随着时效时间的延长变得更加规则致密。这种合金在1100℃/140 MPa条件下的持久寿命为676.5 h,达到第四代镍基单晶高温合金水平。持久断裂后γ’相发生N型筏化,合金中析出针状TCP相(μ相)并在TCP相附近出现位错塞积。在持久试验过程中,合金中生成的γ/γ’界面位错网和a<010>超位错有利于提高其持久性能。

The microstructural evolution during long-term aging at 1000℃and 1130℃and the stress rupture property at 1100℃/140 MPa of a fourth-generation nickel-based single crystal superalloy with 6Re/3Ru were investigated.The microstructure and dislocation configuration of the alloy were observed by field emission scanning electron microscopy(FE-SEM)and transmission electron microscopy(TEM)in terms of its microstructural stability and stress rupture property.The results showed that the alloy displayed excellent microstructural stability.During long-term aging at 1000℃,γ′phase grew up gradually,butγ′phase still remained high cubic degree,however,the TCP phases did not precipitate after aging for 1000 h.After aging at 1130℃for 500 h,theγ′phase connected each other and became rafting ed.The TCP phase started to precipitate after long-term aging at 1130℃for 200 h,however,the content of TCP phase was only 0.04%after aging for 1000 h in the alloy.After aging at 1130℃for 500 h,dislocation networks formed atγ/γ′interfaces which became more regular and denser with the increase of aging time.The stress rupture life of the alloy at 1100℃/140 MPa was 676.5 h,which reached the level of the fourthgeneration nickel-based single crystal superalloy.Theγ′phase underwent N-type rafting,the needle-like TCP phase(μphase)precipitated,and dislocation pile-up was found near TCP phase after fracture.During stress rupture test,the formation ofγ/γ′interfacial dislocation networks and a<010>super-dislocations in the alloy was beneficial to the stress rupture property.