High-energy ultrasonic field effects on the microstructure and mechanical behaviors of A356 alloy

The effects of high-energy ultrasonic field on the microstructure and mechanical properties of A356 alloy are investigated. The results indicate that the long dendritic silicon phases are broken into pieces and the considerable improvement of mechanical properties can be achieved due to the ultrasonic treating. Especially, when the value of the ultrasonic power is 1.2 kW, the distribution of the silicon phase is approximately uniform and the morphology of α-Al phase presents approximate ball-shape. The tensile strength σb, yield stress σs and elongation δ are 293.85 MPa, 207.34 MPa and 6.98%, which are 1.55, 1.93 and 1.10 times to that of without high-energy ultrasonic treating, respectively. These are due to the mechanical effects, cavitation effects and acoustic streaming effects induced by the high-power ultrasonic field. The influence mechanisms of high-energy ultrasonic treatment are discussed in detail.