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利用场发射扫描电镜研究了FGH95粉末冶金高温合金在750℃/5000h时效过程中二次γ′相的尺寸、分布和形貌变化,为其在新型航空发动机中的应用提供理论依据。结果表明,随着时效时间增加,二次γ′相形态不稳定,其尺寸变化不符合体扩散控制的LSW规律。二次γ′相在0~500h发生“反粗化”的分裂,由碟状分裂为块状。在500~1000h阶段分裂的细小γ′相发生粗化,在1000h粗化到一定程度后又开始分裂,2000h后随着时效时间延长又逐渐粗化,椭球状二次γ′相逐渐增多。研究证明,γ′相粒子之间的弹性交互作用是导致其形态变化的主要原因,它属于降低界面能与弹性交互作用能总量的形貌转变机制。
Field emission scanning electron microscopy was used to study the size, distribution and morphological changes of secondary γ ’phase in FGH95 powder metallurgy superalloy at 750 ℃ for 5000h, which provided a theoretical basis for its application in a new type of aeroengine. The results show that, with the increase of aging time, the secondary γ ’phase morphology is unstable, and its size change does not meet the LSW rule of body diffusion control. Secondary γ ’occurs in 0 ~ 500h “anti-coarsening ” of the split, disintegrated from the disk into massive. In the 500 ~ 1000h stage, the fine γ ’phase was coarsened and began to split after being roughed to a certain extent at 1000h. After 2000h, the coarse γ-phase gradually roughened and the secondary γ’-phase increased gradually. Studies have shown that the elastic interaction between γ ’phase particles is the main reason leading to its morphological changes. It belongs to the transformation mechanism of the topography which can reduce the total energy of the interface energy and the elastic interaction energy.