Manipulating the plastic strain delocalization through ultra-thinned hierarchical design for strength-ductility synergy

Realizing strength-ductility synergy of traditional metals and alloys always remains technically challenging. Here we reconcile this trade-off dilemma by engineering Ti/Ti3Al ductile/brittle laminated composites, simultaneously with macroscopically laminated structure and microscopically compositional gradient. Such a kind of previously unidentified laminated/gradient heterogeneous composite exhibits excellent property combinations. Coupling three-dimensional X-ray tomography, in situ straining and digital image correlation (DIC) demonstrated a new microstructure-mediated strain transfer path, stabilizing the plastic flow through the delocalizing of highly localized deformation modes. These findings provide appealing prospects for the design of strong and tough metallic alloys through manipulating plastic strain delocalization as much as possible. (C) 2019 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.