Calorimetric glass transition in bulk metallic glass forming Zr-Ti-Cu-Ni-Be alloys as a free-volume-related kinetic phenomenon

The change of the calorimetric glass transition in Zr46.25Ti8.25Cu7.5Ni10Be27.5 (vit4) bulk metallic glass during differential scanning calorimetry experiments was simulated with the free-volume theory. With the kinetics of the free-volume annihilation and production, calculations carried out on this basis are in good agreement with available experiment data in vit4 alloy both on structural relaxation and the glass transition. The change of the glass transition process is dependent upon the reduced free volume remained in the specimens. The structural relaxation occurring during annealing below the calorimetric glass transition temperature for different times is relative to the annihilation of the excess free volume. The results support that the calorimetric glass transition is a mainly kinetic process.