Characterization of Alloy 600 surfaces after exposure to a caustic environment

The surface morphology and compositions of as-received and electro-polished Alloy 600 surfaces have been studied using Scanning Electron Microscopy and dHej Rutherford Backscattering. The samples were exposed to 1% NaOH with 1% NarCOs solutions over a range of potentials. The as-received surfaces did not show any distinctive changes whereas the electro-polished surfaces were markedly dependent on the underlying metal. Between -90 and 70 mV, relative to a nickel/hydrogen electrode, the active surface showed a distinct grain boundary and grain orientation dependent etching