Relationship between the shear viscosity and heating rate of metallic glasses belowTg

It has been shown that the shear viscosity of bulk and ribbon glassy Pd40 Cu30 Ni10 P20 at temperatures T< Tg (Tg is the glass transition temperature) follows a simple relationship, ln η (T) =B (T) -ln = T, where T - is the heating rate and B depends only on temperature. This means, in particular, that ln η (T) dependencies measured at different heating rates can be superposed by a simple vertical shift and the derivative a∂ ln η/∂ ln T T=const =-1. Such a behavior is indeed found for glassy Pd40 Cu30 Ni10 P20. The experimental viscosity data derived earlier on other metallic glasses follow the same relationship. It is argued that this relationship originates from stress-oriented irreversible structural relaxation with distributed activation energies. © 2006 The American Physical Society