Effects of Ta and Co on Microstructural Stability of a Novel High Strength and Hot Corrosion Resistant Single Crystal Superalloys

Abstract:

The microstructure of hot-corrosion resistant single crystal superalloy with different Ta and Co contents and the microstructure stability during long-term aging at 1000 ℃ was investigated. The results show that in the single crystal superalloy of the experiment, the dissolution temperature of γ" phase increases with the increase of Ta content, the size of γ" phase first increases and then decreases after complete heat treatment. The dissolution temperature of γ" phase decreases and the size of γ" phase and the content of γ" phase reduces with the increase of Co content. During the long-term aging process at 1000 ℃, the coarsening rate of γ" phase first decreases and then increases with the increase of Ta content, while the coarsening rate of γ" phase decreases with the increase of Co content. The mismatch degree of γ/γ" phase and the diffusion of elements in matrix are the main factors affecting the coarsening rate of γ" phase in the four alloys. In addition, Ta increases the content of γ" phase, promotes the distribution of Re, W, Mo and Cr in γ matrix, and promotes the precipitation of TCP phase, while Co reduces the distribution of Re, W, Mo and Cr in γ matrix, reduces the supersaturation of matrix and inhibits the precipitation of TCP phase.

Key words:Ta; Co; hot-corrosion resistant single crystal superalloy; microstructural stability