固溶与时效温度对新型粉末高温合金组织和性能的影响

Effect of solution and aging temperature on microstructure and properties of a new powder superalloy

采用JMatPro、光学显微镜(OM)、场发射扫描电镜(FEG-SEM)、电子探针(EPMA)和透射电镜(TEM)研究了固溶与时效温度对新型粉末高温合金NPM01显微组织的影响,分析了合金组织和性能的关系。结果表明:NPM01合金经1160~1190℃亚固溶+740~920℃两级时效热处理后,合金中有热等静压过程中未溶解的大尺寸一次γ′相,导致二次γ′相析出数量减少,减弱了γ′相的强化作用;经1190~1220℃过固溶+740~920℃两级时效热处理后,二次γ′相长大至240 nm,沿<100>晶向的棱边中心向内凹陷,出现分裂的现象,三次γ′相粗化至70 nm;经1190~1220℃过固溶+740~890℃两级时效热处理后,二次与三次γ′相体积分数之和达到56%,二次γ′相形态稳定,排列整齐,显著增加了γ′相的强化效果,提高了合金高温强度,750℃/750 MPa条件下持久寿命达到437 h,综合力学性能最佳。

The effect of solution and aging temperature on the microstructure of the new designed alloy was studied by JMatPro、OM、FEG-SEM and EPMA.The relationship between microstructure and mechanical properties of the alloy was analyzed.The results show that the non-dissolved large-sizeγ′phases in the alloy lead to the reduction of secondaryγ′phase after heat treatment at 1160-1190℃+740-920℃,which meant the strengthening effect ofγ′phase is reduced.After heat treatment at 1190-1220℃+740-920℃,the secondaryγ’phases grow up to 240 nm and tertiaryγ’phases grow up to 70 nm.Secondaryγ’phases split because its center of<100>edge pitted inward.After heat treatment at 1190-1220℃+740-890℃,the volume fraction of secondary and tertiaryγ′phases is 56%,and the morphology of secondaryγ′phases is stable and regularly arranged,which significantly increases strengthening effects of theγ′phase and the high temperature strength of the alloy.After that heat treatment,the rupture life of the alloy is up to 437 h under the condition of 750℃/750 MPa,and the comprehensive mechanical properties are the best.