Enthalpy recovery and free volume relaxation in a Zr44Ti11Ni10Cu10Be25 bulk metallic glass

We report on the free volume of the Zr44Ti11Ni10Cu10Be25 bulk metallic glass in terms of its enthalpy recovery and volumetric relaxation below the glass transition temperature, T-g. Glassy samples are isothermally annealed below T-g using differential scanning calorimetry and the resulting enthalpy recovery, Delta H-r, is measured upon re-heating into the supercooled liquid region. Volumetric changes below T-g are measured isothermally using Thermo-Mechanical Analysis. The total changes in the relative free volume, Delta v(f)/v(m), between the initially glassy state and the equilibrium liquid are calculated from the volumetric relaxation. The measured values of Delta H-r and Delta v(f)/v(m) correlate well within the framework of free volume theory and a linear relationship is found between the two. (C) 2010 Elsevier B.V. All rights reserved.