Influence of annealing on the microstructure and mechanical properties of Ti/Al and Ti/Al/Nb laminated composites

Ti/Al-based composites and intermetallic compounds attracted great attention due to their good mechanical properties combined with low density. In the present work, Ti/Al and Ti/Al/Nb laminated composites were fabricated by diffusion bonding and subsequent rolling. The fabricated samples were then annealed at different temperatures below and above the melting temperature of pure aluminum. The results indicate that by annealing of the samples at temperatures lower than the melting point of aluminum, a dense and continuous layer of TiAl3 and NbAl3 intermetallic are formed. But during annealing at temperatures higher than the melting point of aluminum a dense layer of TiAl3 particles is formed at Ti/Al interface and a layer of distributed (Ti,Nb)Al-3 intermetallic phase is formed at the Al/Nb interface. The mechanical properties demonstrate that the samples annealed at 650 degrees C have the highest tensile strength. The investigation of the kinetics of phase formation shows that the growth of TiAl3 and NbAl3 layers are controlled by diffusion and reaction at 600-650 degrees C, respectively. Whereas, the growth of TiAl3 layer at 700 degrees C obeys reaction-controlled kinetics. (C) 2018 Elsevier B.V. All rights reserved.