Anodic dissolution of rapidly quenched amorphous Ni81P19 alloys of different initial melt temperatures

The anodic behaviour of rapidly quenched Ni₈₁P₁₉ samples prepared at different melt temperatures was investigated in 1.0 mol dm^–3 aqueous HCl solution. The electrochemical properties of the alloys kept in melt at different temperatures are significantly influenced by the initial melt temperature. X-ray diffractometry suggests that this behaviour is associated with the presence of different quantities of crystalline secondary phase(s). On the basis of potentiodynamic polarization curves and potential-time functions recorded at constant current the alloys were characterized by a charge per surface unit amount proportional to the secondary phase content. A new model was proposed to characterize the anodic dissolution of alloys containing crystalline clusters.