Heterogeneous flow during high-pressure torsion

high-pressure torsion (hpt) has attracted significant attention in recent years as an effective technique to process ultrafine and nanostructured materials. the hydrostatic pressure developed during processing prevents the occurrence of cracks and the low thickness to diameter ratio provides the opportunity for developing high strains at low numbers of rotations. the present work analyses the plastic flow during hpt. experimental results and computer modeling are used to describe heterogeneous plastic flow. it is shown that variations in structure, hardness and in the distribution of strain are observed along the disc thickness. the sources of these heterogeneities are discussed.