Abstract: The viscosity of bulk metallic glass(BMG) Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5(Vit1) around glass transition was derived from the static extension method. In addition, the diffusion coefficient of the medium size atom Fe in the BMG Vit1 was calculated by using the Stokes-Einstein relation. The temperature dependence of both viscosity and diffusion coefficient of the atom Fe, could also be well fitted by two different Arrhenius equations at temperatures below and above the glass transition temperature. In the glass state, the effects of heating rate on viscosity and diffusivity were significant due to the structure relaxation. Besides, it was indicated that the linear plots between lnD₀ and E_D for above and below glass transition are just the same. The results suggest that the intrinsic diffusion of medium size atoms in BMGs, above and below glass transition, is possibly collective hopping processes.

Key words: bulk metallic glass; Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5; glass transition; viscosity; diffusivity