Strengthening-softening transition in yield strength of nanotwinned Cu

JW Xiao and HZ Yang and HX Liu and F Younus and B Xu and XY Zhang and YB Wang and B Wen, SCRIPTA MATERIALIA, 162, 372-376 (2019).

DOI: 10.1016/j.scriptamat.2018.11.049

It is known that the strength of nanotwinned copper increases with decreasing twin thickness, reaches a maximum at twin thickness of 15 nm, and then decreases with twin thickness down to 4 nm. To understand this behavior, critical resolved shear stresses of various slip modes in nanotwinned copper are investigated using molecular dynamics simulations. Based on the Sachs polycrystalline model, twin thickness dependent yield strengths are deduced that are in good agreement with experimental data. The strengthening-softening behavior is attributed to a transition from partial dislocations slipping in twin boundaries to detwinning induced by incoherent twin boundary migration. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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