evolution of texture in an ultrafine and nano grained magnesium alloy

the evolution of texture was discussed during the formation of ultra-fine and nano grains in a magnesium alloy severely deformed through accumulative back extrusion (abe). the microstructure and texture obtained after applying multiple deformation passes at temperatures of 100 and 250°c were characterized. the results showed that after single abe pass at 100°c an ultrafine/nano grained microstructure was obtained, while the initial texture was completely replaced by a new fiber basal texture, inclined at 40°c to the transverse direction. as the processing temperature increased to 250°c, the obtained texture intensities were strengthened, though the c-axis of crystals gradually rotated towards the transverse direction and a fiber texture parallel to normal direction was developed. moreover, repetitive abe was associated with the tendency of the basal plane to lie parallel to td, while the orientation of the prismatic planes showed a random distribution around nd. after eight passes, the most noticeable texture obtained included the fiber basal texture oriented almost parallel to the transverse direction, and perpendicular to the ed and parallel to the nd. the maximum texture intensity decreased as the number of passes increased, which is attributed to strain path change involved during each consecutive abe pass, as well as promoted the contribution of non-basal slip systems.