Substantial Study of Viscosity in Metallic Supercooled Liquids

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(1)Constitutional equations showing the temperature and strain rate dependence on the viscosity were established using a stretched exponential function for supercooled liquids of La_<55>Al_<25>Ni_<20>, Zr_<65>Al_<10>Ni_<10>Cu_<15>, Pd_<40>Ni_<40>P_<20> and Pt_<60>Ni_5P_<25>. The coefficient of the stretched exponential function of the metallic supercooled liquids was in the ranging from 0.82 to 0.90, showing higher uniform structure than polymer supercooled liquids.(2)The fragility of the metallic supercooled liquids was 54,46,35 and 30 for Pd_<40>Ni_<40>P_<20>, Pt_<60>Ni_5P_<25>, La_<55>Al_<25>Ni_<20> and Zr_<65>Al_<10>Ni_<10>Cu_<15>, respectively. The metal-metalloid supercooled liquids of the Pd_<40>Ni_<40>P_<20> and Pt_<60>Ni_5P_<25> exhibited more fragile than the metal-metal supercooled liquids of the La_<55>Al_<25>Ni_<20> and Zr_<65>Al_<10>Ni_<10>Cu_<15>. The metallic supercooled liquids had an intermediate fragility between the strong liquid of SiO2 and the fragile liquid of o-terphenyl.(3)Although the famous Vogel-Fulcher-Tammann relation gave a good description of the metallic supercooled liquid in the neighborhood of the glass transition temperature, sufficient description of the viscosity was not obtained both for supercooled liquid and melt. The equilibrium viscosity over the entire temperature range can be well fitted by the Cohen-Grest free-volume relation.