Size dependent plasticity of a Zr-based bulk metallic glass during room temperature compression

The plastic deformation of Zr65Cu17.5Ni10Al7.5 bulk metallic glass with different diameters (Ø 1–4 mm) but the same initial atomic-scale structure was investigated through compression at room temperature. It was found that the plastic strain increases with decreasing sample dimension, and this tendency becomes more prominent when the diameter of the specimen decreases to 1 mm, indicating a size dependent plasticity. Correspondingly, the morphology of sheared surface also shows size dependence. The fracture surface is characterized by typical vein-like patterns for the sample with large diameter, but for the small size sample, the sheared surface exhibits regular spaced striations. The origin of shear-banding instability that is responsible for the size dependent plasticity is discussed in terms of the adiabatic heating and the free volume model.