Deformation behavior and fracture mechanism of laminated Ti/Ti–50Nb composite fabricated by spark plasma sintering

The laminated Ti/Ti–50Nb composite (laminated Ti–Ti(Nb)) was designed and fabricated by spark plasma sintering (SPS) with alternately stacking pure Ti and Ti–50Nb sheets. The as-sintered composite exhibits a good combination of strength and ductility. Electron backscatter diffraction and digital image correlation was applied to study the grain orientation and strain evolution process during the tensile deformation. The layered structure could help relieve strain localization and the laminated Ti–Ti(Nb) has a total elongation equivalent to that of pure Ti. In the meanwhile, the tensile strength of the laminated Ti–Ti(Nb) and the stress-strain curves before necking can be analyzed by applying the rule of mixture. With the increase of strain, the microvoids initiated, grown and coalesced at the Ti/Ti(Nb) interface, and some of them further expanded into cracks which separated the laminated Ti–Ti(Nb) into several units with fewer layers.