Creep Deformation of Zr₅₅Co₂₅Al₁₅Ni₅ Bulk Metallic Glass Near Glass Transition Temperature: A Nanoindentation Study

Using the nanoindentation technique, the creep deformation behavior of Zr₅₅Co₂₅Al₁₅Ni₅ bulk metallic glass (BMG) in the range of 0.94–1.03 glass transition temperature (T_g) and different loading rates was studied. The Maxwell–Voigt model was applied to describe the deformation and relaxation kinetics of BMGs near the glass transition. According to the results, the serrated behavior of deformation, as the indicator of shear events, disappeared at higher loading rates and temperatures. This event was due to the high rate of defect formation and propagation at higher temperatures under the indenting process. Based on the Maxwell model, it was found that the creep deformation can be divided into two distinct characteristic relaxation times in the range of 0.1–0.68 S and 8.3–24.8 S, respectively. At the higher temperatures, the creep deformation tends to have higher relaxation times, which corresponds to the viscoplastic behavior of material.