Solidification behavior and segregation characteristics of high W-content cast Ni-Based superalloy K416B

Abstract

The solidification behavior of high W-content cast Ni-Based superalloy K416B has been investigated by DTA measurement, isothermal solidification experiment, and Thermo-calc simulation. The element segregation characteristic during solidification was also analyzed by EPMA. The results show that the solidification path of K416B can be summarized as follows: L → L + γ (1371 °C); L → L + γ + M6C (1370 °C); L → L + γ +MC (1332 °C); L → L + eutectic (γ + γ′) (1286 °C); L → MC (High Hf) (1147 °C). During the crystallize of primary γ dendrite, W and Co were enriched in the solid phase, while Cr, Al, Ti, Nb and Hf were enriched in the residual liquid. The positive segregation elements piled up at the remaining liquid promoted the formation of MC carbides and eutectic (γ + γ′). MC carbides precipitated at the interdendritic region and broke the residual liquid network, eutectic (γ + γ′) seemed instability and easily translated into eutectic γ′ by the remelting of γ phase and the coarsening of γ′ phase during subsequent cooling. The solidification terminated by the formation of MC (High Hf) phase.