The interface structure and its impact on the mechanical behavior of TiAl/Ti₂AlNb laminated composites

In this work, the Ti₂AlNb/TiAl laminated composite is successfully fabricated by hot pressing combined with the foil-foil metallurgy. The microstructure and the orientation relationship of the phases in the interface region, the distribution of strain and hardness along the interface, and the stress releasing mechanisms by the plastic deformation accompanied with two types of dislocation sources near the interface are detailly discussed. The composite presents an obvious yield phenomenon in contrast with the TiAl alloy and shows an improved tensile strength at room temperature. Further, an enhanced strength-ductility synergy at high temperature has been achieved. The synergetic deformation ability between the interface and the base alloys, deformation behaviors, and the effects of the laminated structure on crack distribution and morphology are also carefully investigated. The excellent mechanical performances of the composite are attributed to the outstanding metallurgical interface bonding, the introducing of ductile Ti₂AlNb alloy into the laminated composite and the well-coordinated deformation ability of the laminated structure. The presented findings provide a new structural design strategy for property optimization of TiAl alloys.