一种单晶高温合金的组织和持久性能

Microstructure and stress rupture properties of a single crystal superalloy

研究了一种第二代单晶高温合金的显微组织和不同条件下的持久性能.研究结果表明合金铸态组织由γ相、γ′相和共晶相组成.完全热处理后,无共晶和初熔,γ′相立方化较好.合金不同条件下持久性能良好.在760℃/800 MPa条件下持久断裂为类解理断裂,而合金980℃/250 MPa、1 100℃/140 MPa的高温持久断裂显示出韧窝断裂特征.持久断裂组织分析表明,在760℃/800 MPa条件下,γ′相仍保持立方状.在980℃/250 MPa条件下,γ′相发生筏排化.在1 100℃/140 MPa条件下,γ′相筏排化更严重.

The microstructure and stress rupture properties at three different conditions of the second generation single crystal superalloy has been investigated.The results show that the γ matrix, γ′ phase and eutectic can be seen in the as-cast microstructure of the alloy.There are no eutectic and incipient melting and good cubicγ′ phase in the alloy after strandard heat treatment.The alloy has excellent stress rupture properties at different conditions.The fracture mechanism of stress rupture of the alloy at 760 ℃/800 MPa shows quasi-cleavage mode and the fracture mechanism at 980 ℃/250 MPa and 1100 ℃/140 MPa shows dimple model.The morphology of γ′ phase is almost no change at 760℃/780 MPa.The γ′ rafts form at 980 ℃/250 MPa and 1100 ℃/140 MPa and the thickness of rafts increases with the temperature increasing.