Nanoindentation study of Ti-based metallic glasses

The mechanical properties of Ti-based metallic glasses prepared with different cooling rates have been carried out using nanoindentation at different loading rates. The effect of applied loading rate and sample size on the deformation was studied. It is found that lower loading rate promotes serrations or pop-in events. The gradual disappearance of pop-in events observed on load-displacement (P-h) curves represents a transition from discrete shear band activity at low loading rates to the simultaneous operation of multiple shear bands at higher loading rates. The pop-in size was observed to be load or contact depth dependent. An obvious creep displacement, sensitive to loading rates, was observed during the holding period at the maximum load. The cooling rate employed in sample preparation significantly influences the nano-mechanical properties of the metallic glasses, in that the ribbon sample exhibits lower hardness, incipient plasticity at lower applied load and greater pile-up height than bulk samples.