On the origin of the extremely high strength of ultrafine-grained Al alloys produced by severe plastic deformation

Ultrafine-grained Al alloys produced by high-pressure torsion are found to exhibit a very high strength, considerably exceeding the Hall-Petch predictions for ultrafine grains. This phenomenon can be attributed to the unique combination of ultrafine structure and deformation-induced segregations of solute elements along grain boundaries, which may affect the emission and mobility of intragranular dislocations. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.