In-situ synthesis of Al2O3-reinforced high Nb-TiAl laminated composite with an enhanced strength-toughness performance

In this work, the Al2O3-reinforced high Nb-TiAl laminated composite is successfully fabricated by an innovative way of direct-current magnetron sputtering combined with the foil-foil metallurgy, with assistance of vacuum hot-pressed sintering. Here, the Nb-coated aluminum foil and titanium foil, microstructure evolution, the lamellar plane distribution and the mechanical performances are carefully studied. Specifically, the composite is composed of the alpha(2)-Ti3Al, gamma-TiAl and alpha-Al2O3 phase, in which the high Nb-TiAl matrix has a fully lamellar microstructure and a high content (similar to 6.5%) of Nb. Taken the textured titanium foil as raw material, the multi-stage annealing process is proved to be an effective way to control the lamellar plane distribution in the high Nb-TiAl matrix, showing that 82.3% of the lamellar planes forms an angle less than 30 degrees from the RD-ND plane of the composite. Moreover, the bending strength and fracture toughness of the composite reach 817 MPa and 12.41 MPa m(1/2), respectively. Further, the toughening and strengthening mechanisms are also detailly discussed. We believe that the major findings in this work can provide a new idea to design the high strength-toughness intermetallic-ceramic composites.