Effects of High Density Ultrasonic Field Coupling on the Microstructures and Properties of Al-Si Alloy
The effects of high density ultrasonic field coupling on the microstructures and properties of Al-12Si alloy were investigated. It is shown that when the melt undergoes ultrasonic coupling processing prior to solidification, the nucleation rate of liquid phase can be raised to make α(Al) dendrite transform towards near equiaxed grains, the growth of Si phase is restrained and eutectic Si microstructure is refined due to acoustic streaming effect and thermal mechanism; When the melt undergoes ultrasonic coupling processing during the melt solidification, large degree of supercooling is produced in the liquid phase in the solidification interface front edge to reduce the critical radius of crystal nucleus and critical work of nucleation and break up, rupture by melting and refine the Si phase to improve obviously the strength of Al-12Si alloy due to its cavitation effect, acoustic streaming action and heat undulation; The crushing effect of ultrasonic coupling on Si phase occurs mainly during the crystallizing solidification and threshold sound intensity exists.
Yungang Li, Pengcheng Wang, Liqun Ai, Xiaoming Sang and Jinglong Bu
Y. L. Li et al., "Effects of High Density Ultrasonic Field Coupling on the Microstructures and Properties of Al-Si Alloy", Advanced Materials Research, Vols. 291-294, pp. 1981-1988, 2011