Kinking nonlinear elasticity, damping and microyielding of hexagonal close-packed metals

The hexagonal close-packed metals, Ti, Mg, Co, Zr and Zn are of immense technological importance and have been studied extensively for the past 70 years. Despite this large amount of work, the nature of damping and microyielding in these metals has remained unclear. Herein we show that both can be explained by invoking the formation of incipient kink bands (IKBs). IKBs are fully reversible dislocation-based loops that are nucleated on the easy slip planes of plastically anisotropic solids. The results obtained agree exceptionally well with our analytic model that not only successfully explains damping and microyielding, but also allows for the estimation of the critical resolved shear stresses of easy system glide dislocations and the dislocation densities. Based on this and our previous work, it is now apparent that IKBs represent the last piece in the deformation-of-solids puzzle, without which it is impossible to understand their early deformation. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.