The formation of β-FeSiAl5 and BeFe phases in Al7Si0.3Mg alloy containing Be

Thermal analysis and interrupted quench experiments have been carried out to study the formation of β-FeSiAl5 and (BeFe)-BeSiFe2Al8 phases in Al7Si0.3Mg alloy with and without Be addition. In the base alloy with 0.6% Fe (without Be addition), a needle- and plate-shaped β-phase is present in the interdendritic regions and is formed by a ternary eutectic reaction. In the Be-added alloy with 0.6% Fe, a BeFe phase of Chinese script and polygon shapes grows along with the primary α-Al dendrites, leading to superior mechanical properties. It is proposed that this BeFe phase is formed by a peritectic reaction. Be addition has also resulted in some grain refinement.