Effect of melt-to-solid volume ratio and preheating temperature on Mg/Al bimetals interface by centrifugal casting

Compound casting is an efficient method for bonding dissimilar metals, in which a dramatic reaction can occur between the melt and solid. The centrifugal casting process, a type of compound casting, was applied to cast Al/Mg dissimilar bimetals. Magnesium melt was poured at 700 degrees C, with melt-to-solid volume ratios (V-m/V-s) of 1.5 and 3, into a preheated hollow aluminum cylinder. The preheating temperatures of the solid part were 320, 400, and 450 degrees C, and the constant rotational speed was 1,600 rpm. The cast parts were kept inside the casting machine until reaching the cooling temperature of 150 degrees C. The result showed that an increase in preheating temperature from 320 to 450 degrees C led to an enhanced reaction layer thickness. In addition, an increase in the V-m/V-s from 1.5 to 3 resulted in raising the interface thickness from 1.2 to 1.8 mm. Moreover, the interface was not continuously formed when a V-m/V-s of 3 was selected. In this case, the force of contraction overcame the resultant acting force on the interface. An interface formed at the volume ratio of 1.5 was examined using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), and the results demonstrated the formation of Al3Mg2, Al12Mg17 and (delta+Al12Mg17) eutectic structures in the interface.