Viscosity of the supercooled liquid and relaxation at the glass transition of the Zr 46.75Ti 8.25Cu 7.5Ni 10Be 27.5 bulk metallic glass forming alloy

Abstract

The flow and relaxation of the Zr 46.75Ti 8.25Cu 7.5Ni 10Be 27.5 bulk metallic glass forming alloy was investigated in the supercooled liquid state and the glass transition region using parallel plate rheometry, three-point beam bending as well as differential scanning calorimetry. The results indicate that this bulk metallic glass former is a strong liquid that, kinetically, behaves in a similar way as a silicate melt. The relaxation of the viscosity and specific heat capacity was investigated in isothermal experiments and with constant heating rates. The studies reveal that the relaxation of the viscosity into its equilibrium state is directly related to the calorimetric glass transition. The observed calorimetric glass transition in this strong glass former is of a purely kinetic nature and a thermodynamically metastable amorphous state cannot be observed in this bulk metallic glass forming liquid on a laboratory time scale. The heating rate dependence of the calorimetric glass transition reflects the fragility of the liquid.