Observation of slip bands in polycrystalline aluminum deformed in tension.

Slip bands formed at lower strain region ranged from 0.01 to 2% in polycrystalline aluminum were investigated by optical microscopy and crystallographic orientation analysis using a SEM-ECP method. Many of grains exhibited slip bands caused by the primary slip system at 0.01% strain. Half of them produced new additional slip bands caused by the secondary slip system with increased plastic deformation. While, some grains showing slip bands formed by the secondary slip system alone at the initial stage of plastic deformation (0.01% strain) produced slip bands due to the primary slip system with further plastic deformation. Short slip bands were frequently observed at 2% strain near the grain boundaries. The slip system of this slip bands had very small Schmid factor. The phenomenon of this slip system becoming active could not be explained by the several theories proposed for the bicrystal deformation.