长期时效对定向凝固高温合金DZ9组织和性能的影响

Effests of Long-Term Exposure on Microstructure and Mechanical Property of Directionally Solidified Superalloy DZ9

研究了二代定向凝固高温合金DZ9长期时效后的显微组织和力学性能的变化规律。研究结果表明,合金经900℃长期时效,随着时效时间的延长,γ′相尺寸略有增加,γ′相基本上呈立方形态分布;时效后晶界上的碳化物产生了二次析出,沿晶界析出链状碳化物。随着时效时间的增加,室温σb和σ0.2均呈下降趋势,拉伸塑性变化则相反;760℃和980℃持久寿命,随着时效时间的延长,持久寿命变化不大。合金具有较好的组织稳定性。

The effects of long-term exposure on microstructure and mechanical property were studied for directionally solidified superalloy DZ9. The results indicate that the size of γ′ phase increases gradually and the morphology of γ′ phase is cuboidal yet. The secondary carbides M6 C and M23C6 were precipitated after ageing, which appeared at the grain boundary. With the increasing of long-term exposure time, the tensile strength decreases gradually and there is higher ductility. The stress-rupture life keeps higher when exposed for 1000 h at 900 ℃. DZ9 alloy exhibits excellent microstructure stability.