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采用SEM、FEG-SEM、TEM和EDS等测试方法研究一种先进超超临界机组用新型高温合金Inconel 740在固溶处理、沉淀硬化处理和750℃时效3 000 h过程中的组织稳定性。结果表明,固溶处理状态下的Inconel 740组织晶粒度3～4级,一些颗粒尺寸大的一次(Nb、Ti)C和TiN弥散分布于γ基体上,γ′相形核于晶内;沉淀硬化处理主要在晶内共格析出γ′相,在晶界析出大量的M23C6和少量的G相;750℃长期时效条件下,γ′相发生Ostwald熟化,颗粒粗化,γ晶界逐渐被G相占据,并且时效300 h时在晶界附近开始析出针状的η相,随时效的持续,η相长大并趋向于呈现魏氏组织形态。Inconel 740的组织稳定性有待于进一步改善。
SEM, FEG-SEM, TEM and EDS were used to study the tissue stability of Inconel 740, an advanced ultra-supercritical unit with solution treatment, precipitation hardening and aging at 750 ℃ for 3 000 h. The results show that the grain size of Inconel 740 in the solution treatment is in the range of 3 to 4, and some primary (Nb, Ti) C and TiN with large grain size disperse on the γ matrix and the γ ’ During the long-term aging at 750 ℃, Ostwald maturation occurred in the γ ’phase and the grain coarsening, and the γ grain boundary was gradually replaced by G Phase occupies, and the needle-like η phase precipitates in the vicinity of the grain boundary at 300 h aging. With aging, η phase grows and tends to present Widmanstatten morphology. The tissue stability of Inconel 740 needs to be further improved.