The Solidification Segregation and Homogenization Behavior of a New Solid‐Solution Strengthened Ni‐Based Superalloy: Key Effects of Zr Microalloying

In this article, zirconium (Zr) microalloying plays a crucial role in regulating the solidification, segregation, and homogenization kinetics of a newly developed solid‐solution strengthened Ni‐based superalloy. Three alloy variants with distinct Zr contents (0.02, 0.08, and 0.22 wt%) are comprehensively analyzed using transmission electron microscopy, electron probe microanalysis, and scanning electron microscopy equipped with energy dispersive X‐ray spectroscopy. The results show that Zr addition significantly widens the solidification temperature range ΔT (23, 26, and 36 °C), which aggravates interdendritic segregation of Zr, Mo, and Mn. Zr‐rich MC carbides (0.036, 0.131, and 0.249 wt%) that precipitate at grain boundaries undergo progressive dissolution during homogenization at 1200 °C and are accompanied by an increase in the diffusion coefficients of elements (Cr: 4.99, 5.78, and 6.63 × 10 −15 m 2 s −1 ; Mo: 3.85, 5.31, and 6.55 × 10 −15 m 2 s −1 ). Consequently, an appropriate amount of Zr microalloying can facilitate elemental diffusion throughout the homogenization process. However, an excessive Zr addition will trigger severe elemental segregation during solidification, which has a detrimental impact on the hot workability of subsequent alloys. Finally, the synergistic effect is thoroughly discussed, and the optimal Zr content is determined.