Insights into crystallographic and topographic characteristics of local corrosion attack on zinc

Abstract

Through large area crystallographic analysis across the whole cross-section of a 0.5 mm zinc wire by backscattered electron diffraction (EBSD) excavated by plasma focused ion beam (pFIB) and topographic analysis by scanning electron microscopy (SEM), the crystallographic and topographic characteristics of corrosion on zinc are identified and correlated. Striated domains dominating the surface are the result of preferential dissolution of non-basal planes leaving (0001) plates intersecting the surface. Remnant fragments of zinc lie close to the original surface which is due to the combined effects of the initial protective film on the surface and the crystallographic corrosion. Three corrosion layers were found, namely from the outside inwards, a highly porous outer layer, a densified intermediate layer and an attacked layer.