Localization of shear strain and shear band formation induced by deformation in semi-solid Al-Cu alloys

Abstract

In situ observation of deformation in globular Al-Cu samples at a solid fraction of ∼⃒50% and a global shear strain rate of 10-1 s-1 was performed using time-resolved X-ray imaging. The solid particle motion during shear was quantitatively analysed. The force was transmitted though the contacts between solid particles over a long distance parallel to the shear plane (18 mean grain size, d) after only a 1d increment of the Al2O3 push-plate motion. On the other hand, the distance of transmitted force in the perpendicular direction to the shear plane was restricted to approximately 11d even for a high displacement of the Al2O3 push-plate. A relatively high shear strain rate became localized at the shear domain after a small amount of deformation (a 1d increment). The solid fraction decreased in the region of localized shear strain rate. The shear band width, where the shear strain was localized and the solid fraction decreased, remained mostly unchanged over a 4 d increment of Al2O3 push-plate motion.