Newtonian to non-Newtonian master flow curves of a bulk glass alloy $Pd40Ni10Cu30P20$

The viscosity and flow stress of a bulk $Pd40Ni10Cu30P20$ alloy glass near the glass transition were measured as a function of temperature and strain rate under compression. The steady-state viscosity of the glass for a given temperature remains constant at low strain rate, then decreases by many orders of magnitude above a critical strain rate. A master curve in term of the viscosity ratio $η/ηN$ and the product $ηNε̇$ has been constructed, where η and $ηN$ are, respectively, the steady-state viscosity and Newtonian viscosity, and $ε̇$ is the strain rate. The flow stress also can be represented in terms of the product $ηNε̇.$ The master curves are fitted with a simple stress relaxation of the form $1−exp[−t/λ]$ with $t=ε̇−1.$