Variation in polarized light intensity with grain-orientation in anodized aluminum

Abstract This work concerns light reflected from anodized aluminum polycrystal specimens. First, the crystallographic orientation of the individual grains were obtained by selected area channeling patterns in a scanning electron microscope. The specimens were then anodized, and the grains studied in a light microscope with crossed polarizers. By using a photometer, a relationship was established between the maximum light intensity reflected from a grain and its crystallographic orientation. The results reflects a strong relationship between the optical properties of the anodic film and the crystallographic orientation of the grain on which the film is formed. Hence, the well-known technique of studying anodized aluminum specimens in polarized light can be extended to include information about the orientation of the different grains. The method is sensitive enough for studying subgrain misorientations.