한국주조공학회

Fabrication of high strength Mg-Li-Al alloys by squeeze casting was established by the stabilization of melt and mold temperatures, applied pressure and the refining method. The entrapment of inclusions during pouring was prevented using 30 ppi alumina foam filter. The as-cast microstructure consists of a mixture of α and β phases including AILi and MgLi_2, Al particles, which are distributed in the β matrix. The grain sizes of gravity and squeeze casting alloys were 288 μм and 207 μм respectively. The addition of Al in Mg-Li alloys promoted the formation of second phase particles, which were adjusted to optimize the properties of Mg-Li-Al alloys. The Mg-10wt%Li-5wt%Al alloy after heat treatment at 350℃ for 1 hour showed the maximum hardness value. This is due to the facts that the amounts of α and β phases and their distributions are dependent upon the solution treatment temperature, and that the amounts of AILi and MgLi_2Al particles are dependent upon the Al content.