Texture Evolution in Zr Grain-refined by Equal Channel Angular Pressing

초록

To explore a possibility of obtaining an ultra fine grain size in hcp materials, equal channel angular pressing (ECAP) was applied to commercially pure Zr with the initial grain size of 20 micron. To ensure the crack-free specimen during the severe deformation it was necessary to adopt different die design at the two processing temperatures, room temperature and 350C. Sub-micrometer scale grains, in the order of 200 nm, were obtained by employing the die design of 90deg./20deg. and the deformation temperature of 350C. With the proper choice of the processing parameters, the refined grains were surrounded by the high angle boundaries. During the severe plastic deformation, the crystal texture underwent a significant change, from a fiber texture to that of a strong (0002) component mixed with a medium {10-10} components, suggesting a dual <a> slip mode of deformation on the plane of the maximum shear stress.