Viscosity Measurements of Zr{sub}55Cu{sub}30Al{sub}10Ni{sub}5 and Pd{sub}40Cu{sub}30Ni{sub}10P{sub}20 Supercooled Liquid Alloys by Using a Penetration Viscometer

摘要

Viscosity of Zr{sub}55Cu{sub}30Al{sub}10Ni{sub}5 and Pd{sub}40Cu{sub}30Ni{sub}10P{sub}20 supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a cylindrical probe under high speed heating conditions at heating rates between 20 and 400℃/ min in the temperature range from the glass transition temperatures (T{sub}g) up to above the crystallization temperatures, The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200℃/min and above. Their viscosity could be well represented by the Arrhenius relation The activation energies for viscous flow for Zr{sub}55Cu{sub}30Al{sub}10Ni{sub}5 and Pd{sub}40Cu{sub}30Ni{sub}10P{sub}20 supercooled liquid alloys were about 350 and 250kJ/mol, respectively, The viscosity Was also fitted by a Vogel-Fulcher-Tammann (VFT) relationship over the entire temperature range.