Enhancing Plasticity of Bulk Metallic Glass by Controlling Residual Stress

Many bulk metallic glasses (BMGs) are known to have attractive material characteristics such as high levels of strength-to-weight ratio and reasonable toughness, and yet being flexible. Indeed this has led to their use in a wide variety of high performance applications ranging the sports equipment to micromachine components. The study on their mechanical properties is currently a critical topic in BMG research. In particular, shear band formation is thought to be a universal mechanism of the deformation of metallic glasses. The formation of shear bands in BMG during deformation is actually a complex kinetic process. Because of the incomplete knowledge of BMGs structures on an atomic-level, the exact nature of local atomic motion taking place during shear transformation is not fully resolved. In this proposed investigation, the applicant intend to examine the interaction of the defect structure or shear band network generated by pre-compression with the major shear band during compression test. The mechanical properties of BMG specimens with pre-compression treatment will be compared with those of as-cast BMG samples. The results will shed light on the process through which shear bands propagate and multiply in a sample with well-defined residual stress states.