Shear stress induced reduction of glass transition temperature in a bulk metallic glass

In contrast to previous observations of a slight increase in glass transition temperature (Tg) under hydrostatic pressure, we report, for the first time, a drastic reduction of Tg (40 K/500 MPa) induced by shear stress in a Zr46.75Ti8.25Cu7.5Ni10.0Be27.5 bulk metallic glass, which gives rise to the experimental observation of the drastic decrease in flow temperature while a compressive stress was applied. The significant Tg reduction is attributed to a large activation volume of relaxation (delta)V(tau) under shear stress (126 ?3), and can be quantitatively interpreted in terms of the free volume model.