Viscosity measurements of Zr55Cu30Al10Ni5 supercooled liquid alloys by using penetration viscometer under high-speed heating conditions

The viscosity of Zr55Cu30Al10Ni5 supercooled liquid alloys having bulk metallic glass forming ability was measured using a penetration viscometer with a cylindrical probe under at heating rates as high as 400 °C/min. Viscosity decreased with an increase in the heating rate and tended to saturate at 200 °C/min and above. This may partly indicate a decrease in the oxygen contamination from the measuring atmosphere and partly due to differences in structural relaxation during heating at various rates. The viscosity of these alloys can be well represented by an Arrhenius relation. The activation energies for viscous flow with various heating rates were all at values of about 340–350 kJ/mol. Viscosity follows a Vogel–Fulcher–Tammann (VFT) relationship over the entire temperature range.