SURFACE-ROUGHNESS AND METASTABLE PITTING OF AMORPHOUS NICKEL-ALLOY

The effects of surface finish on nucleation and growth of metastable p its on an amorphous Ni-Cr-Fe-Si-B alloy was studied using potentiostat ic and potentiodynamic polarization tests. Nucleation of metastable pi ts on the amorphous alloy was facilitated significantly by a rougher s urface. Both growth rate constants and peak currents of metastable pit s followed a log-normal distribution. A rougher surface also promoted the growth of metastable pits and led to a wider distribution in growt h rates.