Fabrication of wavy γ-TiAl based sheet with foil metallurgy

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.