High thermal gradient directional solidification with liquid metal cooling and its application in the processing of nickel-based superalloys

During directional solidification, thermal gradient in front of the liquid-solid interface (G_L) is important in defining the subsequent cooling rate and the solidification microstructure. An elevated G_L is frequently demanded, especially in the production of directionally solidified and single-crystal superalloys. In this study, some methods for obtaining high thermal gradients have been developed. By using zone-intensified overheating and liquid-metal cooling, high thermal gradients of up to 800 K/cm were achieved. Application of these methods in the processing of directionally solidified and single crystal superalloys indicate that high thermal gradient directional solidification produced more refined and uniform microstructures and therefore optimized mechanical properties.