Structural relaxation and glass transition behavior of novel (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy developed by equiatomic substitution

A series of glass forming alloys (Ti33Zr33Hf33)100−x−y(Ni50Cu50)xAly (x = 20-70 at.% and y = 0-30 at.%) have been developed by equiatomic substitution of similar elements. Of these alloys (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 was chosen in this study to investigate the structural relaxation and glass transition behavior. The as-quenched (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy was fully amorphous and had a wide supercooled liquid region ΔT = Tx(503 °C) − Tg(433 °C) = 70 °C, where Tg and Tx are the glass transition and crystallization temperatures, respectively. Low temperature pre-heat treatments of the (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy for 10 min at 310 °C, 370 °C and 390 °C caused structural relaxation accompanied by the formation of very fine scale lattice ordering. After these heat treatments, the glass transition became hard to observe in the (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy. Increasing the pre-heat treatment temperatures and holding times caused the glass transition to become more clearly detectable with increasing endothermic heat release.