Effect of oxygen impurity on crystallization of an undercooled bulk glass forming Zr-Ti-Cu-Ni-Al alloy

Abstract

High vacuum, containerless, electrostatic levitation process has been used to study the undercooling and crystallization kinetics of a bulk glass forming Zr-Ti-Cu-Ni-Al alloy. The oxygen impurity level in the alloy has been found to play a crucial role in the crystallization kinetics of the undercooled melt. Overheating the melt above a critical threshold temperature results in enhancement subsequent undercooling. This crucial threshold temperature is found to be a function of the overall oxygen content of the alloy direct measurement of the time-temperature-transformation (TTT) diagram for crystallization of the undercooled melt made following initial overheating above the threshold temperature show a strong dependence on overall oxygen concentration. An explanation of these observations is proposed.