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

摘要

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 + gamma (1371 degrees C); L -> L + gamma + M6C (1370 degrees C); L -> L + gamma +MC (1332 degrees C); L -> L + eutectic (gamma + gamma') (1286 degrees C); L -> MC (High Hf) (1147 degrees C). During the crystallize of primary gamma 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 (gamma + gamma'). MC carbides precipitated at the interdendritic region and broke the residual liquid network, eutectic (gamma + gamma') seemed instability and easily translated into eutectic gamma' by the remelting of gamma phase and the coarsening of gamma' phase during subsequent cooling. The solidification terminated by the formation of MC (High Hf) phase. (C) 2020 Elsevier B.V. All rights reserved.