U-based binary strong glass forming system

Fundamental issues of U-based binary metallic glasses (MGs) have been scarcely studied due to their low thermostability and glass forming ability (GFA). In this work, the glass formation in U-Ni system was reexamined. It is found that currently designed U-Ni glassy alloys in the range of 54-75% U show a pronounced thermal glass transition feature for the first time among binary U-based systems, and also have the glass transition temperature (T-g) above 600 K and much stronger thermostability than other similar U-based glasses. The T-g presence contributes to the evaluation of their glass transition activation energy, liquid fragility, viscosity as well as the Kauzmann temperature. Moreover, the fragility value of the typical alloy U69.2Ni30.8 is about 20, almost the same as those of the oxide glass formers SiO2 and GeO2, illustrating that U-Ni is a binary strong glass forming system. The reasons for the remarkable T-g presence and low fragility together with the GFA level of U-based MGs are discussed.