长期时效对两种低Re镍基单晶高温合金显微组织和持久性能的影响

Effect of long-term aging on microstructure and stress rupture properties of two low-Re nickel based single crystal superalloys

采用扫描电镜和蠕变试验机研究了长期时效对两种低Re镍基单晶高温合金(1.0Re和1.5Re合金)显微组织和持久性能的影响。结果表明:在980℃/1000 h的长期时效处理过程中,合金的γ′相发生粗化和连接,1.0Re合金粗化速率略大于1.5Re合金。980℃长期时效过程中两种合金均未析出TCP相,均表现出较好的组织稳定性。持久性能测试表明:200 h长期时效后1.0Re和1.5Re合金在1038℃/172 MPa的持久寿命较热处理态分别提高了16.8%和13.3%;随着长期时效时间的延长,持久寿命略有下降,长期时效1000 h后,1.0Re和1.5Re合金的持久寿命较热处理态分别下降了15.8%和14.9%。3种状态下两种合金持久寿命均相近,说明用0.5%W代替0.5%Re后起到相同的强化效果。

Effect of long-term aging on microstructure and stress rupture properties of two low-Re nickel based single crystal superalloys(1.0Re alloy and 1.5Re alloy)was investigated by means of scanning electron microscopy and creep testing machine.The results show that during long-term aging at 980℃for 1000 h,theγ′phase of the alloy coarsens and connects,and the coarsening rate ofγ′phase of the 1.0Re alloy is higher than that of the 1.5Re alloy.TCP phase is not precipitated in the two alloys during long-term aging at 980℃,and both alloys show good microstructural stability.The results of stress rupture test show that the stress rupture life of the 1.0Re and 1.5Re alloys aged for 200 h at 1038℃/172 MPa is 16.8%and 13.3%higher than that of the heat treated alloy,respectively.With the increase of long-term aging time,the stress rupture life of the two alloys decreases slightly.After long-term aging for 1000 h,the stress rupture life of the 1.0Re and 1.5Re alloys decreases by 15.8%and 14.9%respectively compared with that of the heat treated alloy.The stress rupture life of the two alloys is similar under the three conditions,which shows that the replacing 0.5%Re with 0.5%W has the same strengthening effect.