h a i Prismatic , h a i basal , and h c + a i slip strengths of commercially pure Zr by micro - cantilever tests

Slip strengths of hai basal, hai prism, and hc+ai pyramidal systems in commercially pure zirconium have been determined using micro-cantilever testing. A range of single crystal cantilevers 0.5 lm to 10 lm wide, oriented for single slip were prepared using focused ion beam (FIB) machining and subsequently deflected using a nanoindenter. The critical resolved shear stress (scrss) was found by fitting a crystal plasticity finite element model to the experimental load–displacement data for these micro-bending tests. All the three slip systems in a-Zr show a marked size effect in bending described well by sCRSS(W) = s0 + AW, where W is the cantilever width, s0 is the CRSS at the macro scale and n = 1. The exponent, n, of near 1 is in good accord with hardening caused by the back stress generated by dislocations piling up at a diffuse barrier caused by the reduction of stress near the neutral axis. The macro scale CRSS values were used to successfully simulate deformation of a conventional macroscopic compression test. 2015 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).