The active regulatory effects of magnesium on the preparation, microstructure and mechanical properties of a novel Al-Bi based γ-ray shielding material by casting method

The effects of Mg on the solidification behavior, microstructure and mechanical properties of Al-20Bi immiscible alloy were systematically investigated based on thermodynamic and experimental methods. The results showed that Mg was an interfacial active element to Al-Bi alloy. Mg tended to adsorb on the Al-Bi liquid-liquid interface, resulting in a reduction of the miscibility gap and thus a decrease of the interfacial tension. Al-20Bi and Al-20Bi-3Mg alloys were prepared by casting method. The newly-formed Mg₃Bi₂ particles with high thermal stability were more evenly dispersed in Al-20Bi-3Mg alloy compared to Al-20Bi alloy. Furthermore, Mg₃Bi₂ was a ductile phase with higher strength than that of Bi. It was well elucidated that Mg had an active regulatory effect on the preparation, microstructure and properties of Al-Bi alloy. This research provides a new way for low-cost large-scale preparation of Al-Bi based γ-ray shielding material with high-performance.