DD5单晶高温合金在长期时效和持久性能试验中的γ′相演化

Evolution of γ′ Phase in DD5 Single Crystal Superalloy During Long Term Aging and Stress Rupture Tests

研究了DD5单晶高温合金在热处理态、长期时效态(1 100℃/500 h)和持久性能测试过程中的γ′相演化。结果表明:1 100℃时效500 h后,γ′相全部由立方体形态转化成条状组织,基体通道宽度接近γ′相宽度并析出大量粒状二次γ′相,γ/γ′相界面形成大量错配位错网。与热处理态相比,长期时效态合金在871℃/552 MPa和1 038℃/172 MPa条件下持久寿命明显降低。长期时效态合金在871℃/552 MPa条件下持久试验后,一次γ′相保持长期时效后形态,但基体通道中的二次γ′相形成了N型筏形组织。长期时效态合金在1 038℃/172 MPa条件下持久试验后一次γ′相形成垂直于拉应力的N型筏。

The evolution of γ＇ phase in DD5 single crystal superalloy in the heat treated state, long term aging state （1 100 ℃/500 h） and stress rupture tests has been studied. The results show that after aging at 1 100 ℃ for 500 h, all cubic γ＇ phase in the superalloy was transformed into plate-like structure and the width of the matrix channel was nearly equal to that of γ＇ plate; a large amount of granular secondary γ＇ phase were precipitated, and lots of misfit dislocation networks were formed at theγ＇ interface. Compared with the alloy in the heat treated state, the stress rupture lives of the alloy in the long term aging state under the conditions of 871 ℃ / 552 MPa and 1 038 ℃/172 MPa were decreased obviously. Under the condition of 871 ℃/552 MPa, in the alloy after long term aging, the primary γ＇ phase maintained the plate-like microstructure as in the alloy in the long-term aging state, but the secondary γ＇ phase was transformed into the secondary N type raft microstructure. Under the condition of 1 038 ℃ / 172 MPa in the alloy after long term aging, the primary γ＇ phase was transformed into the N type raft microstructure, which was perpendicular to the tensile stress.