Dynamic mechanical properties in a Zr46.8Ti13.8Cu12.5Ni10Be27.5 bulk metallic glass

The dynamic mechanical response was investigated in a bulk metallic glass Zr46.8Ti13.8Cu12.5Ni10Be27.5 (called Vit4). Mechanical spectroscopy was performed either using continuous heating or isothermal measurements. A main visco-elastic relaxation is observed before the onset of crystallization. A drastic decrease of the storage modulus and a maximum of the loss modulus indicate this relaxation in the amorphous state. The very large activation energy (EA=4.5eV) and the very high value of the pre-exponential factor (τ0-1=2.5x10-35s) indicate that this relaxation involves the collective movement of a large number of atoms, as in many amorphous materials (polymers, oxide or molecular glasses). Master curves are plotted, indicating that the time-temperature superposition principle is obeyed. These master curves can be described using a physical model based on the concept of quasi-point defects. Finally, the elastic, visco-elastic and visco-plastic contributions to the deformation are separated and discussed