CaAl-based bulk metallic glasses with high thermal stability

We report that binary Ca-Al alloys can be readily cast into amorphous rods of 1 mm in diameter. Upon further alloying to depress the liquidus temperature, the amorphous rod diameter is increased to 3 mm. The high glass transition temperature T(g)similar to210degreesC and crystallization onset temperature T(onset)similar to240degreesC or higher observed are attributed to the covalent bonding trend noted in Ca-Al alloys that exhibit complex network structures. Along with a high microhardness value of 200-235 DPH (diamond pyramid hardness) and low mass densities of 2 gm/cm(3), these thermally stable light-metal alloys are recognized as potential structural amorphous metals. (C) 2004 American Institute of Physics.