FORMATION OF La-Al-Ni-Cu-Fe BULK METALLIC GLASSES WITH HIGH GLASS-FORMING ABILITY

Abstract

The effect of alloy composition on improving glass-forming ability of La-based alloys is investigated in this work. Previous composition criteria demonstrated that the alloys with high glass-forming ability should have negative heats of mixing among the main constituent elements. In this study, the addition of Fe to a La-based La-Al-Ni-Cu alloy significantly improved the glass-forming ability, although the heat of mixing between Fe and the main element La is positive. La-Al-Ni-Cu-Fe bulk metallic glasses with diameters up to 15 mm were prepared by the method of pouring the molten alloys into a copper mold. These La-Al-Ni-Cu-Fe bulk metallic glasses exhibit relatively wide supercooled liquid region of about 50 k, and high Trg(Tg/Tl) andγ(Tx/(Tg+Tl)) values. It is found that the addition of Fe to the La-Al-Ni-Cu alloy lowers the Gibbs free energy difference between the liquid and crystalline phases in the supercooled liquid region and enhances the glass-forming ability of the alloy.