Remarkable transitions of yield behavior and Luders deformation in pure Cu by changing grain sizes

Fully recrystallized ultrafine-grained (UFG) pure Cu specimens were fabricated by high-pressure torsion (HPT) and controlled annealing. The recrystallized UFG Cu with a minimum mean grain size of 0.51 pm showed high yield strength, good ductility, obvious yield drop and large Liiders strain during tensile test. The mechanical behavior of the Cu specimen became sensitive to the change in the grain size from 0.2 pm to 4.2 pm. The continuous transitions of yield behavior and Luders deformation with grain sizes were discussed. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.