Microscopic shear localization in nickel

Abstract

Structure and texture evolution was assessed on nominally pure nickel deformed between room tem-perature and 300 °C. Structure evolution below 300 °C consisted of the formation of paired mi-crobands, their transition into microband clusters, the appearance of dislocation bundles between clusters, and the decomposition of bundles into new clusters. Structure evolution at 300 °C entailed the formation of dislocation bundles with wavy boundary extensions from which microband clusters formed and eventually connected. Thermal analysis revealed a vacancy annihilation peak at the lower processing temperatures but none for material rolled at 300 °C. It is proposed that the ease with which cross slip occurs and high vacancy concentration are critical factors for the formation of well-defined microbands. Texture evolution follows the normal fcc transition from brass to copper type textures.