Abstract:A 0.7 mm-thick wavy γ-TiAl sheet with fully lamellar microstructure was fabricated by hot pressing Ti/Al alternate foils with heat treatment of 640 °C, 15 h+850 °C, 35 h+1350 °C, 2 h. The intermetallic compounds formed during heat treatments were identified by scanning electron microscopy (SEM) and X-ray diffraction (XRD). TiAl₃ was the only observed phase at the Ti/Al interface when Al foils were not consumed. After being annealed at 850 °C for 35 h, the microstructure was composed of α-Ti, α₂-Ti₃Al, γ-TiAl and TiAl₂. A fully lamellar microstructure formed after annealing at 1350 °C. Most of the angles between the lamellar interface and the sheet plane are below 30°. Using thinner starting foils is favorable to produce sheets with fine microstructure.

Key words: solid state reaction; phase transformation; titanium aluminides; foil metallurgy