材料期刊网

研究了二代单晶高温合金DD5在980℃无载荷时效处理后的组织及性能变化.结果表明:DD5合金980℃时效后组织基本稳定,5000 h时效后未发现TCP相的析出.980℃时效中,150 h时效后γ'相呈规则立方状并未发生明显长大,平均尺寸达到约0.5 μm,1000 h时,γ '相基本呈立方形态分布,但平均尺寸约1μm,2500 h时γ'相粗化明显,5000 h时基本形成筏状组织.时效后,初生碳化物发生分解并有次生碳化物析出,包括点棒状MC(1),块状富Hf的MC(2),细小质点状M23C6.870℃抗拉强度值随时效时间延长逐渐下降,1000 h后下降5.5％,而5000 h后下降9.8％.持久寿命随时效时间延长呈逐渐递减趋势:980℃/207 MPa的持久寿命,1000 h后下降19％,5000 h后下降了43％;1070℃/140 MPa的持久寿命1000 h后下降38％,5000 h后下降了52％;1093℃/158 MPa的持久寿命1000 h后下降31％,5000 h后下降了52％.

The microstructural evolution and property of the second generation single crystal (SC) superalloy DD5 after long-term aging at 980 ℃ without stress were investigated.The results show that microstructure of the alloy is generally stable after aging at 980 ℃,and no TCP phase is precipitated in the matrix after aging at 980 ℃ for 5000 h.After aging at 980 ℃ for 150 h,no change is observed for the cubic γ' phase,its average size is about 0.5 μm.The average size of the γ' phase is about 1 μm after aging for 1000 h.After aging for 2500 h,γ' phase can coarsen obviously,and it becomes rafting after aging for 5000 h.A part of MC carbides can decompose and the secondary carbides are precipitated after aging,including M C,Hf riched M C(2) and M23C6 particles.The tensile strength of the alloy aging at 870 ℃ is gradually decreased with increasing aging time,which decreases by 5.5％ and 9.8％ after aging for 1000 h and 5000 h,respectively.The stress rupture life of the alloy is also decreased with increasing aging time.The rupture life at 980 ℃ and 207 MPa decreases by 19％ and 43％ after aging for 1000 h and 5000 h,respectively,and the rupture life at 1070 ℃ and 140 MPa decreases by 38％ and 52％ after aging for 1000 h and 5000 h,respectively,and the rupture life at 1093 ℃ and 158 MPa decreases by 31％ and 52％ after aging for 1000 h and 5000 h,respectively.