Formation of Metallic Glasses in Novel (Ti<SUB>33</SUB>Zr<SUB>33</SUB>Hf<SUB>33</SUB>)<SUB>100-x-y</SUB>(Ni<SUB>50</SUB>Cu<SUB>50</SUB>)<SUB>x</SUB>Al<SUB>y</SUB> Alloys

Abstract

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� xy(Ni50Cu50)xAly glassy alloys with compositions in the range x ¼ 10{70 at% and y ¼ 10{30 at%, and with a large supercooled liquid region in the rangeT ¼ TxTg ¼ 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 ¼ 50{70 at%, crystallization took place with a single exothermic reaction, and for (Ti33Zr33Hf33)- rich alloys with x ¼ 20{40 at%, crystallization took place with a series of exothermic reactions. Increasing the Al content from y ¼ 10 to 30 at% decreased the glass forming ability of the amorphous phase for a wide range of transition metal compositions x ¼ 40{70 at%. The most stable amorphous alloy was (Ti33Zr33Hf33)40(Ni50Cu50)50Al10 with a crystallization temperature of Tx ¼ 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 TxTg ¼ 124 K.