Thermal Dependence of Shear Banding in Zr70Ni16Cu6Al8 Bulk Metallic Glasses

Abstract

Zr70Ni16Cu6Al8 bulk metallic glass samples were cast and prepared for tensiletesting. Tensile tests were done at temperatures 77 K, 150 K and 295K, over a range of effective strain rates between 10−5 and 10−1/s in order toassess the dependence of plastic deformation through shear band sliding onthe aforementioned factors.A strong temperature dependence was found, with maximum shear bandsliding distance at 150 K. The sliding distance was also found to increasewith lowered strain rates. The temperature dependence is likely to stemfrom increased heat dissipation suppressing a decrease in viscosity, while thestrain rate dependence stems from a decrease in energy supply rate.Shear bands appeared at higher stresses at lower temperatures, resultingin larger elastic domains and higher ultimate tensile stresses. A mechanismwhere heat dissipation suppresses the formation of shear bands at low stresseswas proposed.v