Crystallization behaviour and viscous flow of Zr50Ni50−xCux metallic glasses under constant heating rate conditions

The crystallization behaviour and viscous flow of some melt spun Zr50Ni50−xCux (10 < x < 20 at.%) amorphous alloys under nonisothermal conditions have been studied using differential scanning calorimetry. The volume transformation kinetics has been considered on the basis of the KJMA equation modified by Krüger to describe it under nonisothermal conditions. It is governed by a nucleation rate which increases along with the increasing heating rate by the transformation, and by the further three-dimensional growth of crystalline nuclei. The temperature dependence of the viscosity has been measured by creep measurements under nonisothermal conditions. It has been theoretically interpreted on the basis of the Free Volume Model further modified for the case of nonisothermal viscosity measurements.