Growth kinetics of metastable pits on sputtered nanocrystalline stainless steel

The development of metastable pit on sputtered nanocrystalline stainless steel was investigated in 3.5 wt.% NaCl solution. Its current transient is distinct from that of conventional coarse-grained stainless steel. The remnant thin membrane passive film over the pit mouth was found to act as a diffusion barrier, however, it do not undergo continuous rupture during the metastable growth, which restricted the diffusion rate of metal cations away from the pit and kept the current constant. The effect of remnant thin membrane passive film on the growth of metastable pit and its transition to stability has been discussed.