Effects of Melt/Solid Volume Ratio and Rotational Speed on the Interface of Al/Mg Bimetal in Centrifugal Casting

In this study, centrifugal casting process was used for producing Al/Mg bimetal. Molten Mg was poured at 700 oC, with 1.5 and 3 melt-to-solid volume ratio (Vm/Vs) into the 450 oC preheated solid Al rotating at 800, 1200, 1600 and 2000 rpm. Castings were kept inside the centrifuged casting machine and cooled down to 150 oC. Investigating the effect of melt-to-solid volume ratio showed that increasing volume ratio from 1.5 to 3 results in diminishing metallurgical bonding in Al/Mg interface, because the force of contraction overcomes the resultant force acted on the interface. The results of study by scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) showed that bimetal compounds of Al3Mg2, Al12Mg17 and δɝ瘲ൻ eutectic structure (δ is the solid solution of Mg in Al) are formed in the interface. Atomic force microscopy (AFM) image of Al surface showed that the surface was rough in atomic dimentions, which can result in the formation of gas pores in the interface.