Pure shear stress reversal on a Cu-based bulk metallic glass reveals a Bauschinger-type effect

We have developed a torsion machine that can apply pure shear stress to small-diameter rod samples. We report preliminary results on Cu-based metallic glass samples held at constant torque in the elastic range. The inelastic angle of twist increases approximately linearly with the logarithm of time, interpreted as anelastic deformation. Reversal of torque reveals an effect analogous to the Bauschinger effect in polycrystalline metals. The relative deformation rate is increased by a factor of 4.5 on first reversal, an effect discussed in terms of the operation of shear transformation zones and related to structural change in the metallic glass. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.