Microstructural evolution in ultrasonicated AS41 magnesium alloy

The present study evaluates the effect of high intensity ultrasound on the microstructural modification of AS41 alloy. Various microstructures are produced in this alloy by employing ultrasonic vibrations at different temperatures and for different durations. The results clearly show that in the absence of ultrasonication, the dendrites of primary α-Mg phase are coarser and non-uniform in size. Upon ultrasonication of the alloy melt, nearly uniform and globular/equiaxed grains with a network of β-Mg 17Al 12 and Mg 2Si intermetallic phases segregated along the grain boundaries are obtained. The average grain size decreased gradually with increase in ultrasonic treatment time. Grain refinement mechanisms involved in the development of microstructure are discussed.