Shear banding behavior and fracture mechanisms of Zr55Al10Ni5Cu30 bulk metallic glass in uniaxial compression analyzed using a digital image correlation method

Abstract

The shear banding behavior and fracture mechanisms of a Zr55Al10Ni5Cu30 bulk metallic glass (BMG) were investigated using uniaxial compression tests equipped with a digital image correlation (DIC) method system. The DIC results captured the shear bands correctly, and the Zr-based BMG exhibited two deformation modes depending on the strain rate. In the fast mode under a strain rate of 1.0 x 10(-2) s(-1), multiple shear banding was observed. The effects of shear band interactions were observed in the DIC results, and the results were analyzed in terms of the serrated plastic flow. The stair shaped fracture pattern and slipped vein pattern found on the fracture surface were strong evidence of the shear band interactions. However, the plastic deformation was confined to a few shear bands without shear band interactions in the slow mode under a strain rate of 1.0 x 10(-4) s(-1). From quantitative analyses, it was found that the shear bands propagated progressively rather than simultaneously at the beginning of the shear band formation. Then, the propagation became simultaneous after the shear band formation was completed through the entire shear planes. This progressive propagation behavior caused strain heterogeneity, which increased after each reactivation event. Also, two shear bands propagated simultaneously without interactions in the direct observations, which represented a load drop in serrated flow. Furthermore, it was revealed that there were different fracture mechanisms depending on the strain rate and deformation mode. This comprehensive quantitative analysis of the shear banding behavior and fracture mechanisms of BMGs enables better understanding and design of superior BMGs. (C) 2012 Elsevier Ltd. All rights reserved.