Tension-compression asymmetry of ⟨c plus a⟩ slip in Ti-6Al

Microcantilevers with triangular cross-sections were machined using a focused ion beam from an a Ti-6Al alloy. Plasticity was predominantly in the lower part of the cantilever, allowing tension-compression asymmetry to be investigated by bending the cantilever up or down. Both (a) prismatic slip and < c + a > pyramidal slip were investigated. The critical resolved shear stress was determined by calibrating a crystal plasticity model and found to be 329 MPa for < a > prismatic slip in both tension and compression. However significant tension-compression asymmetry was observed for < c + a > pyramidal slip; increasing to 820 MPa under compression and decreasing to 558 MPa in tension. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd.