Deformation behavior and fracture mechanism of laminated Ti/Ti-50 Nb alloy with diffusion layer

The laminated Ti /Ti-50 Nb alloy (laminated Ti-TiNb alloy) was designed and fabricated by spark plasma sintering (SPS) combined with hot rolling. TEM and EBSD were applied to investigate the microstructure and texture evolution before and after the tensile deformation. In-situ tensile tests monitored by SEM were applied to understand the fracture behavior of laminated Ti-TiNb alloy. The results indicated that the laminated structure and diffusion layer endowed the laminated Ti-TiNb alloy with enhanced strength-ductility synergy. The formation of the diffusion layer effectively strengthened the laminated Ti-TiNb alloy due to the precipitation of a large number of fine second phases. During the tensile deformation, the diffusion layer deformed in coordination with the component layers, so that the strain efficiently transferred between the Ti and the TiNb layers. Simultaneously, grain rotation in the TiNb layers was apparently promoted which suppressed premature strain concentration within the TiNb layers. An excellent strain hardening ability was achieved in the laminated Ti-TiNb alloy with diffusion layers, with a uniform elongation of 9.4%, much higher than the value calculated by the rule of mixture. At last, the relationship between interface status and fracture behavior was discussed.