⟨a⟩ Prismatic, ⟨a⟩ basal, and ⟨c plus a⟩ slip strengths of commercially pure Zr by micro-cantilever tests

Slip strengths of < a > basal, < a > prism, and < c+a > pyramidal systems in commercially pure zirconium have been determined using micro-cantilever testing. A range of single crystal cantilevers 0.5 mu m to 10 um wide, oriented for single slip were prepared using focused ion beam (FIB) machining and subsequently deflected using a nanoindenter. The critical resolved shear stress (tau(crss)) 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 alpha-Zr show a marked size effect in bending described well by tau(CRSS)(W) = tau(0) + AW(n), where W is the cantilever width, tau(0) is the CRSS at the macro scale and n = similar to-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. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd.