Multilayered Ti-Al intermetallic sheets fabricated by cold rolling and annealing of titanium and aluminum foils

Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils. The microstructure and phase formation of the obtained sheets under different sintering conditions were evaluated by various techniques. The results reveal that when the sintering temperature is above the melting point of aluminum, the self-propagating high-temperature synthesis reaction occurs between Ti and Al, and forms various phases of Ti-based solid solutions including α-Ti Ti₃Al, TiAl, TiAl₂ and α-Ti including TiAl₃, etc. When the sintering time increased, Ti-based solid solution, TiAl₂ and TiAl₃ disappeared gradually, and the sheet containing Ti ₃Al and TiAl phases in a multilayered structure formed finally. A lot of voids were also observed in the sintered structures, which were caused by the melting Al, Kirkendall effect and the difference of molar volumes between reactants and products. The voids were eliminated and a dense sample was obtained by the following hot press.