Ultrasound-induced distribution of nano-sized TiB₂ particles within α-Al grains during solidification of Al-7Si alloy

This research proposed an effective approach by introducing ultrasound into the solidification process of Al-7Si melt containing nano-sized TiB₂ particles with the aim of inducing more TiB₂ particles to distribute within α-Al grains. Experimental results showed that the ultrasound was able to promote α-Al nucleation on more TiB₂ particles, since the undercooling of melt and enhancement of the diffusion velocities of heat and solute induced by ultrasound could improve the nucleation efficiency of α-Al on TiB₂ particles. In addition, ultrasound could make TiB₂ particles more susceptible to engulfment by moving solid/liquid interface due to the ultrasonic effects of improving the wettability between TiB₂ and α-Al and promoting TiB₂ particles random motion.