Strain rate dependent plastic mutation in a bulk metallic glass under compression

This paper reported a strain rate dependent plasticity in a Zr-based bulk metallic glass (BMG) under axial compression over a strain rate range (1.6 x 10 (5)-1.6 x 10 (1) s (1)). The fracture strain decreased with increasing strain rate up to 1.6 x 10 (3) s (1). A "brittle-to-malleable" mutation occurred at strain rate of 1.6 x 10 (2) s (1), subsequently, the macro plasticity vanished at 1.6 x 10 (1) s (1). It is proposed that the result is strongly related to the combined action of the applied strain rate, the compression speed, and the propagating speed of the shear band. When the three factors coordinated in the optimal condition, multiple mature shear bands were initiated simultaneously to accommodate the applied strain, which propagated through the specimen and distributed homogeneously in space, dominating the overall plastic deformation by consuming the entire specimen effectively. (C) 2011 Elsevier Ltd. All rights reserved.