Refining efficiency and capability of top-down synthesis of nanocrystalline materials

Severe plastic deformation (SPD) has been employed in recent years as a top-down method for the synthesis of nanocrystalline materials. In this paper, data reported for various severe plastic deformation processes, including high pressure torsion (HPT), equal channel angular pressing (ECAP), ball milling (BM), and accumulative roll bonding (ARB), are analyzed in terms of: (a) the minimum grain size obtainable by SPD processing, (b) the capability and feasibility of individual processing techniques, and (c) refining efficiency in terms of grain size decrease as a function of induced strain.