Formation of Metallic Glasses in Novel (Ti₃₃Zr₃₃Hf₃₃)100-x-y(Ni₅₀Cu₅₀)xAly Alloys

The formation of metallic glasses by rapid solidification has been studied using an equiatomic substitution technique. This paper reports results on a series of (Ti33Zr33Hf33)100−x−y(Ni50Cu50)xAly glassy alloys with compositions in the range x=10–70 at% and y=10–30 at%, and with a large supercooled liquid region in the range ΔT=Tx−Tg=40 to 124 K where Tx = crystallization onset temperature and Tg = glass transition temperature. The crystallization of the glassy alloys was studied by a combination of X-ray diffraction and differential scanning calorimetry. For (Ni50Cu50)-rich alloys with x=50–70 at%, crystallization took place with a single exothermic reaction, and for (Ti33Zr33Hf33)-rich alloys with x=20–40 at%, crystallization took place with a series of exothermic reactions. Increasing the Al content from y=10 to 30 at% decreased the glass forming ability of the amorphous phase for a wide range of transition metal compositions x=40–70 at%. The most stable amorphous alloy was (Ti33Zr33Hf33)40(Ni50Cu50)50Al10 with a crystallization temperature of Tx=818 K. However the amorphous alloy with the largest supercooled liquid region was (Ti33Zr33Hf33)60(Ni50Cu50)20Al20 with a crystallization-glass transition temperature difference of Tx−Tg=124 K.