Processing sheet materials by accumulative roll bonding and reaction annealing from Ti/Al/Nb elemental foils

The high Nb containing TiAl based alloy, Ti–46Al–9Nb (at.%), was produced using accumulative roll bonding (ARB) followed by two-stage reaction annealing from Ti, Al, and Nb elemental foils. Well-bonded sheet materials were successfully obtained with an initial rolling reduction of 50%. Two-stage annealing of 600 and 1400 °C was employed to promote the formation of intermetallic compounds. The cooling rate was controlled to produce the lamellar structure. The scanning electron microscopy and X-ray diffraction indicated that there were no room temperature solid-state reactions between the Ti/Al/Nb foils, even at 10 cycles. Besides the annealing time and temperature, rolling strain also has a significant effect on the production of the intermetallic compound. Differential thermal analysis was used to characterize the effect of rolling strain on the solid-state reaction and phase formation in the composites during annealing. It is clear that the first annealing stage produced a complete reaction of the Al layers forming the intermetallic compounds TiAl3 and NbAl3. The desired composition and structure of the intermetallic compounds were achieved after the second stage annealing.