Study of non-isothermal primary crystallization kinetics of Al84Ni12Zr1Pr3 amorphous alloy

The primary crystallization kinetics of amorphous Al84Ni12Zr1Pr3 alloy has been studied using non-isothermal differential scanning calorimetry (DSC) measurements. The apparent activation energies for the two crystallization stages determined by the Kissinger and Ozawa methods are in good agreement. The local activation energies Ec(α) are determined by an isoconversional method and its average value is about 342.72 kJ/mol. Both DSC traces and X-ray diffractometry (XRD) patterns show that the first crystallization stage with the apparent activation energy of 384.6 kJ/mol, in which fcc-Al precipitates, is a rapid two- and three-dimensional diffusion-controlled nucleation and growth mechanism for bulk crystallization initially. Afterwards, it is mainly dominated by one-dimensional growth of Al crystallites at a near-zero nucleation rate for surface crystallization. The nucleation activation energy (En) and growth activation energy (Eg) of fcc-Al are about 200-230 kJ/mol and 360-388 kJ/mol, respectively. For the second transformation stage, the residual amorphous phase transforms into several intermetallic compounds with the apparent activation energy of 234.3 kJ/mol.