Deformation behavior of brittle/ductile multilayered composites under interface constraint effect

Abstract A brittle/ductile multilayered composite was designed and fabricated by reaction annealing of pure Ti and Al foils, and comprised alternating α-Ti(Al) layer, α+α 2 dual-phase layer, and α 2 -Ti 3 Al layer. Brittle α 2 -Ti 3 Al phase is expected to impart high yield strength to the composite, while the ductile α-Ti(Al) phase provides the desired tensile ductility. The role of α+α 2 dual-phase layer is to weaken the deformation incompatibility between α-Ti(Al) and α 2 -Ti 3 Al layers. As expected, tensile tests show a good strength-ductility combination. The real-time tracking of local strain evolution process during the tensile deformation provides a new perspective in understanding the relationship between the microstructure and mechanical properties, by which we found the strength-ductility synergy originates from the constrained crack propagation behavior and strain non-localization imparted by multilayered structure. During the tensile deformation, the local Ti 3 Al cracking firstly occurred, and the size of plastic zone at the crack tip was theoretically predicted and experimentally validated. Additionally, a model was proposed to describe the stress/strain transfer path before and after cracking.