Titanium aluminide sheets made using roll bonding and reaction annealing

The process of roll bonding and reactive annealing was used to process γ-titanium aluminide sheets with a nearly fully lamellar microstructure. Cold roll bonding was employed to bond elemental titanium and aluminum foils. A two stage annealing treatment initially at 600 °C and then at 1300 °C resulted in a two phase (γ + α2) structure along with Kirkendall porosity. Hot rolling of the sheet followed by a heat treatment at 1400 °C resulted in a nearly fully lamellar microstructure and denser material compared to sheet that was not subjected to hot rolling. The process parameters and resulting microstructures are presented. Mechanical properties of the processed sheet were measured and found to be comparable to those in the literature for bulk material processed by foil metallurgy. Thus the processing approach presented for the Ti–Al binary alloy is found to be viable for the processing of gamma titanium aluminide sheets.