The radiation induced segregation (RIS) was studied by electron/helium dual-beam irradiation. Within agrain, the content of Cr and Mn were higher in the center than at the margin of the irradiated areas. In thecontrar...The radiation induced segregation (RIS) was studied by electron/helium dual-beam irradiation. Within agrain, the content of Cr and Mn were higher in the center than at the margin of the irradiated areas. In thecontrary, withim the irradiated areas included grain boundaries the contents of Cr and Mn decreased at the grainboundaries. RIS was weaker under dual-beam irradiation than that under electron single-beam irradiation, whichwas because of the increases of dislocation density and sink strength of voids when helium existed.展开更多
Multimodal size distribution of γ′ phase was obtained in a slow-cooling experiment following supersolvus solution treatment(1191°C). The morphology of the secondary γ′ particles exhibited splitting and protru...Multimodal size distribution of γ′ phase was obtained in a slow-cooling experiment following supersolvus solution treatment(1191°C). The morphology of the secondary γ′ particles exhibited splitting and protrusion instabilities. In the subsequent aging process(815°C), reverse coarsening was observed, i.e., the average precipitate size decreased with increasing aging time.Reverse coarsening slows the coarsening rate of the precipitates, increases the hardness of the alloy, and greatly improves the morphological stability of the γ′ phase.展开更多
The effect of Ta on the microstructures of nickel-based powder metallurgy superalloys with different Ta contents was investigated in experiments and thermodynamic calculations. The Ta element predominantly occupied t...The effect of Ta on the microstructures of nickel-based powder metallurgy superalloys with different Ta contents was investigated in experiments and thermodynamic calculations. The Ta element predominantly occupied the γ′ phase of the superalloys, with some incursion into the γ phase, and minimal presence in the MC carbide. By substituting part of the Ti-Nb alloy,the Ta element transforms(Ti-Nb)C into(Ti-Ta-Nb)C. The MC carbides and small amounts of M23C6 carbides were observed on the ribbon-like grain boundaries. The Ta addition little affected the primary γ′ phase, but greatly influenced the secondary γ′phase. Ta promoted the splitting of the secondary γ′ phase, converting it to a more stable state. Increasing the Ta content increased the lattice constants of γ′ and γ and altered the degree of misfit between γ′ and γ, indicating a morphology change. The Ta content also influenced the formation of the tertiary γ′ phase.展开更多
文摘The radiation induced segregation (RIS) was studied by electron/helium dual-beam irradiation. Within agrain, the content of Cr and Mn were higher in the center than at the margin of the irradiated areas. In thecontrary, withim the irradiated areas included grain boundaries the contents of Cr and Mn decreased at the grainboundaries. RIS was weaker under dual-beam irradiation than that under electron single-beam irradiation, whichwas because of the increases of dislocation density and sink strength of voids when helium existed.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFB0700505)the National Natural Science Foundation of China(Grant No.51571020)+1 种基金the State Key Laboratory for Advanced Metals and Materials(Grant No.2016-Z05)the fund of the Guangdong Provincial Key Laboratory for Technology and Application of Metal Toughening(Grant No.GKL201611)
文摘Multimodal size distribution of γ′ phase was obtained in a slow-cooling experiment following supersolvus solution treatment(1191°C). The morphology of the secondary γ′ particles exhibited splitting and protrusion instabilities. In the subsequent aging process(815°C), reverse coarsening was observed, i.e., the average precipitate size decreased with increasing aging time.Reverse coarsening slows the coarsening rate of the precipitates, increases the hardness of the alloy, and greatly improves the morphological stability of the γ′ phase.
基金supported by the National Natural Science Foundation of China(Grant No.51571020)the National Key Research and Development Program of China(Grant No.2016YFB0700505)+1 种基金the State Key Laboratory for Advanced Metals and Materials(Grant No.2016-Z05)the Fund of the Guangdong Provincial Key Laboratory for Technology and Application of Metal Toughening(Grant No.GKL201611)
文摘The effect of Ta on the microstructures of nickel-based powder metallurgy superalloys with different Ta contents was investigated in experiments and thermodynamic calculations. The Ta element predominantly occupied the γ′ phase of the superalloys, with some incursion into the γ phase, and minimal presence in the MC carbide. By substituting part of the Ti-Nb alloy,the Ta element transforms(Ti-Nb)C into(Ti-Ta-Nb)C. The MC carbides and small amounts of M23C6 carbides were observed on the ribbon-like grain boundaries. The Ta addition little affected the primary γ′ phase, but greatly influenced the secondary γ′phase. Ta promoted the splitting of the secondary γ′ phase, converting it to a more stable state. Increasing the Ta content increased the lattice constants of γ′ and γ and altered the degree of misfit between γ′ and γ, indicating a morphology change. The Ta content also influenced the formation of the tertiary γ′ phase.
