Uniaxial and biaxial compressive response of a bulk metallic glass composite over a range of strain rates and temperatures

The uniaxial and biaxial compressive responses of Zr57Nb5Al10Cu15.4Ni12.6-W composite were investigated over a range of strain rates (similar to 10(-3) to 10(3) S-1) using an Instron universal testim, machine (similar to 10(-3) to 10 degrees s(-1)), drop-weight tower (similar to 200 s(-1)), and split Hopkinson pressure bar (10(3) s(-1)). The temperature dependence of the mechanical behavior was investigated at temperatures ranging from room temperature to 600 degrees C using the instrumented drop-weight testing apparatus, mounted with an inductive heating device. The deformed and fractured specimens were examined using optical and scanning electron microscopy. Stopped experiments were used to investigate deformation and failure mechanisms at specified strain intervals in both the drop weight and split Hopkinson bar tests. These stopped specimens were also Subsequently examined using optical and scanning electron microscopy to observe shear band and crack formation and development after increasingly more strain. The overall results showed an increase in yield strength with strain rate and a decrease in failure strength, plasticity, and hardening with strain rate. Comparison of uniaxial and biaxial loading showed strong susceptibility to shear failure since the additional 10% shear stress caused failure at Much lower strains in all cases. Results also showed a decrease in flow stress and plasticity with increased temperature. Also notable was the anomalous behavior at 450 degrees C, which lies between the T-g and T-x and is in a temperature regime where homogeneous flow, as opposed to heterogeneous deformation by shear banding, is the dominant mechanism in the bulk metallic glass.