Crystallization of amorphous iron-nickel-phosphorus alloys prepared by electrodeposition

The crystallization behaviour of amorphous Fe-Ni-P alloy electrodeposits has been studied over a wide range of compositions using both isothermal and dynamic annealing methods. X-ray and electron diffraction along with microhardness measurements were used to monitor the crystallization process. Isothermal crystallization kinetics suggests mainly a growth process on pre-existing random nuclei. No evidence of metastable intermediate phases was found in isothermally crystallized alloys. The activation energy for crystallization is very sensitive to the phosphorus content of the alloys. The decrease in the activation energy and enthalpy for crystallization imply a greater degree of supersaturation with increase in the phosphorus content. Both enthalpy and activation data suggest that 10 wt.% phosphorus is the critical concentration to obtain an amorphous rather than microcrystalline structure.