New insight into fabrication of shaped Mg–X alloy foams with cellular structure via a gas release reaction powder metallurgy route

Shaped Mg alloy foams with closed-cell structure are highly interested for a great potential to be utilized in the fields where weight reduction is urgently required. A powder metallurgical method, namely gas release reaction powder metallurgy route to fabricate Mg–X (X=Al, Zn or Cu) alloy foams, was summarized. The principles on shaped Mg–X foams fabrication via the route were proposed. In addition, the effects of alloying elements, sintering treatment and foaming temperatures on fabrication of shaped Mg–X alloy foams were investigated experimentally. The results show that the key to ensure a successful foaming of Mg–X alloy foams is to add alloying metals alloyed with Mg to form lower melting (< 600 °C) intermetallic compounds by the initial sintering treatment. The foaming mechanism of Mg–X alloy foams also has been clarified, that is, the low-melting-point Mg-based intermetallic compounds melt first, and then reactions between the melt and CaCO₃, a foaming agent, release CO gas to make the precursor foamed and finally shaped Mg–X alloy foam with a promising cellular structure is prepared. This route has been verified by successful fabrication on shaped Mg–Al, Mg–Zn and Mg–Cu foams with cellular structure.