“…Minor variations in distribution of strain along the sample thickness has been predicted by finite element modelling 40,41 due to friction and variations in hardness distribution have been reported in samples with low diameter to thickness ratio 39,42 . However, experiments have shown significant heterogeneity in hardness distribution along the disc thickness in a magnesium alloy in samples with high diameter to thickness ratio 43,44 . Moreover, it is known that the high amount of defects introduced by plastic deformation leads to the formation of low angle boundaries in the early stage of processing and the misorientation of these boundaries increase with continuing processing.…”