Effect of Isothermal Annealing on Crystallization Mechanism of Amorphous Ni 65 Cr 16 P 19 Metallic Alloys

Crystallization behavior of amorphous Ni 65 Cr 16 P 19 metallic alloy during the isothermal annealing process from 617 K to 648 K was studied using differential scanning thermal analysis and X-ray diffraction analysis. Two crystallization peaks are observed. The activation energies E A for the crystallization are determined to be 403 kJ/mol and 306 kJ/mol for the first and the second peak, respectively. Ni crystals precipitate in the first peak by a two-dimensional crystallization mechanism with a constant nucleation rate, and stable Ni 3 P crystallizes in the second peak. With the use of the Avrami index, the activation energy for nucleation of the Ni crystal is determined to be 470 kJ/mol.