Enthalpy relaxation of the Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 bulk metallic glass forming alloy

A new experimental method was developed to study the isothermal enthalpy relaxation kinetics below the glass transition region of bulk metallic glass forming alloys using differential scanning calorimetry. The method was applied to the Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 alloy and the results reveal that the enthalpy relaxes in an Arrhenius-like fashion. The activation energy obtained from the Arrhenius fit is comparable to the activation energy required for the diffusion of the medium size atoms. This suggests that solid-state diffusion is the governing mechanism for the enthalpy relaxation process. The stretching exponents for the relaxation are close to unity, which indicates that this alloy is a rather strong glass former. This is confirmed by Vogel–Filcher–Tammany (VFT) fits of the heating rate dependence of the glass transition.