Effect of ultrasonic field on centerline segregation of cast aluminum alloy 7050 ingots

By introducing ultrasonic field during the solidification process of aluminum alloy melt, the effects of ultrasonic treatment (UST) on macroscopic and microscopic segregation were investigated. The results show that under 170W of UST, the macrosegregation degree of Zn is diminished to the minimum, the segregation index reaches 0.0583. At a higher ultrasonic intensity, the UST greatly contributes to the positive centerline segregation in the ingot. Compared with conventional casting (without UST), the solid solubility of Zn, Cu and Mg inside crystals of ultrasonic casting can be strengthened so that the microsegregation tends to be minimized. Overall, the ultrasonic cavitation and acoustic stream promote the redistribution of solute elements in the ingots, and a reasonable ultrasonic power is beneficial to weaken the segregation.