时效处理对一种新型粉末高温合金组织和性能的影响

Effects of aging heat treatment on the microstructure and properties of a new type nickel-based PM superalloy

对一种新型粉末高温合金进行不同时效处理,观察析出相和显微组织,测试合金室温、高温(750、815℃)拉伸和高温(750℃/750 MPa、815℃/450 MPa)持久性能,分析不同时效处理对合金组织和性能的影响。结果表明:过高的二级时效温度导致γ′相发生Ostwald熟化,减弱了γ′相的强化效果,导致合金的室温、高温强度降低,持久寿命明显缩短。单纯的一级时效,导致二次γ′相未发生进一步长大,三次γ′相微量析出,合金的强度提高,高温塑性显著降低。试样经HT2制度热处理后,二次与三次γ′相匹配良好,γ′相尺寸适当,未发生熟化,强度略有降低,塑性明显提高,综合力学性能优异。

The precipitation phases and microstructure of a new type PM superalloy with aging treatments were observed. The tested mechanical properties were listed as follows :room temperature,750 ℃ and 815 ℃ tensile,750 ℃/750 MPa stress rupture,and 815 ℃/450 MPa stress rupture. The effects of different aging treatments on the microstructure and properties of the alloy were analyzed. The results show that high secondary aging temperature leads to Ostwald ripening of γ′ phase,which weakens the strengthening effect of γ′ phase,decreases the room temperature and high temperature strength of the alloy,and shortens the rupture life obviously. The single stage aging results in no further growth of the secondary γ′ phase,and tertiary γ′ phases doesn′t precipitate. The strength of the alloy increases and the plasticity at high temperature decreases significantly. After HT2 heat treatment,the secondary and tertiary γ′ phase match well,the size of γ’ phase is appropriate,the strength is slightly decreased,the plasticity is obviously improved,and the comprehensive mechanical properties are excellent.