Effect of boron addition on functionally graded microstructure of centrifugally cast Al-13.8 wt.% Mg2Si cylinders

The effect of boron additions on microstructure of in-situ Mg2Si/Al composite has been previously studied in conventionally cast processes. In current research, regarding the potential of the centrifugal casting for segregation ofmicrostructural components during solidification, the effect of boron addition on radial grading of microstructure incentrifugally cast Al-13.8 wt.% Mg2Si cylinders has been studied. Two cylinders were centrifugally cast with chemical composition of Al-13.8 wt.% Mg2Si containing 0.5 percent (weight) Al-5B master alloy and boron-free, respectively. By comparing the microstructures of boron-content and boron-free cylinders in radial directions, the most important microstructural changes were observed in outer periphery of the boron-content cylinder where represented the fine eutectic cells as well as some primary Mg2Si particles in microstructure. This microstructural result was attributed to centrifugally segregation of boron atoms towards the outer periphery of the cylinder. Induction coupled plasma (ICP) analyses in radial direction of the boron-content cylinder confirmed a gradient in boron concentration from 11.099 ppm in outer layer to 1.248 ppm in inner layer

Keywords:

Functionally graded microstructure , Centrifugal casting , Al-13.8 wt. %Mg2Si alloy , master alloy , segregation