Etch Patterns On Zone-Refined Fe

Upon dissolution of zone-refined Fe in strong acids, mainly three kinds of corrosion patterns were observed in the crystallites of the sections. Regardless of the acids, the {110} plane always appeared on the three patterns in the form of smooth and even steps, ledges, or facets. The {112}, {122}, and {123} planes were also developed but to a much lesser degree. The {100} and {111} planes were not observed because grains of the respective orientation were missing on the sections. Attempts were made to explain the formation of the planes by taking into consideration the reticular density of the planes and the frequency of their appearance. The theoretical relative corrosion rates of the separate crystallographic planes were estimated. The trend obtained agreed with the observed rates. © 1970, The Electrochemical Society, Inc. All rights reserved.