Post-bonded compressive behavior and processing map of TiAl/Ti₂AlNb joint along the bonding interface based on a composite model

Post-bonded compression of TiAl/Ti₂AlNb joint was conducted between deformation temperatures 950 °C and 1050 °C, with the strain rate range of 0.001 s⁻¹–0.0001 s⁻¹ and the height reduction of 50% in the present work. And the hot deformation behavior of the joint was investigated based on an analysis of the strain-stress curve, Arrhenius constitutive equation and processing map. The Arrhenius relationship (AR) and the parallel Arrhenius relationship (PAR) were established to describe the flow stress as a function of the strain rates and deformation temperatures. As a consequence, the average error between the AR and the PAR was only 1.1%, showing that the bonding interface has a feeble influence on the hot compression process of the joint. Moreover, an optimized processing map of the joint was constructed by overlaying the macro-instability map on the interfacial microstructure control region. The stability region of the joint was defined to this domain with the deformation temperature higher than 1050 °C and the strain rate lower than 0.0005 s⁻¹. On balance, this work can be used to not only improve the hot working ability of the joint but also develop the interfacial microstructure of the joint.