Heterostructured titanium composites with superior strength-ductility synergy via controllable bimodal grains and <c+a> dislocation activity

Constructing heterostructures in particulate reinforced titanium matrix composites (PRTMCs) to evade the strength-ductility trade-off dilemma is much more difficult than in metals. Here, we proposed a novel and controllable strategy of simple powder assembly to fabricate bimodal-grained PRTMCs, this customized strategy makes coarse grains (CGs) surrounded by ultrafine-grained (UFG) matrices, conferring a superior strength-ductility combination not achievable by their traditional homogeneous counterparts. We found that such heterostructures appear to promote storage of mostly dislocations in CGs and accumulation near the CG/UFG boundaries. Moreover, hybrid reinforcements also activate multiple hardening mechanisms, inducing high ductility.