长期时效对DD6单晶高温合金组织和力学性能的影响

Effect of long term aging on microstructure and mechanical properties of DD6 single crystal superalloy

采用螺旋选晶法制备DD6合金单晶试棒,标准热处理后在980℃长期时效2000 h,研究980℃长期时效对DD6单晶高温合金的组织演化及力学性能的影响。结果表明:随着长期时效时间的延长,合金中γ′相的尺寸增大,2000 h后γ′相尺寸约为1μm,没有TCP相析出,合金具有较好的组织稳定性。2000 h长期时效试样在980℃/243 MPa下持久寿命为180.16 h,为热处理态的56.3%;在1070℃/130 MPa下持久寿命为144.42 h,为热处理态的35.31%,断裂模式均为微孔聚集型断裂;相比热处理态的合金,2000 h长期时效态试样760℃的抗拉强度和屈服强度分别降低5.55%和5.88%;980℃的抗拉强度和屈服强度分别下降11%和10.59%。

DD6 single crystal superalloy specimens were prepared by spiral crystal selection method.After standard heat treatment the long term aging at 980℃was performed for 2000 h.The influences of the microstructural evolution and mechanical properties of DD6 single crystal superalloy after long term aging at 980℃were studied.The results show that with the prolongation of long term aging time,the size ofγ′phase in the alloy increases.After long term aging for 2000 h,the size ofγ′phase is about 1μm,and there is no TCP phase precipitation,which shows that DD6 alloy has good microstructural stability.The stress rupture life of sample after long term aging for 2000 h is 180.16 h at 980℃/243 MPa,which is 56.3%of heat treated state,and 144.42 h at 1070℃/130 MPa,which is 35.31%of heat treated state.The fracture mode is microvoid coalescence fracture.The tensile strength and yield strength of the alloy after long term aging for 2000 h are reduced by 5.55%and 5.88%at 760℃,and 11%and 10.59%at 980℃,respectively.