Enhanced strength-ductility synergy of honeycomb-like titanium matrix composites via strain delocalization and slip activation

Honeycomb-like heterostructural titanium matrix composites (HTMCs), featuring soft Ti6Al4V cores and hard TiB/Ti6Al4V composite shells, were fabricated. The HTMCs with various cell sizes (Φ1.0, Φ0.8, Φ0.5, Φ0.4 and Φ0.3) exhibit higher work hardening rates (WHRs) than homogeneous counterparts. The superior WHR is attributed to the activation of pyramidal dislocation slip near the hetero-interfaces, as well as strain delocalization, which postpones tensile necking. The tensile strength and uniform elongation of Φ0.5 (991 MPa, 7.66%) are increased by 10.5% and 96.9% compared with the Ti6Al4V alloy. A smaller cell size weakens the WHR because the grains within the soft core region are refined.