Performance assessment of TiNb_f/TiAl composites with different fiber structural characteristics

Continuous TiNb fiber reinforced TiAl composites (TiNb_f/TiAl) have tremendous potential for substituting brittle TiAl alloy to service on advanced aerospace equipment. This study has clarified microstructure evolution of TiNb_f/TiAl composites and successfully achieved the structure modification of TiNb fiber by aging process where strengthening phase α-Ti could precipitate homogeneously in basket shape at the core of fiber meanwhile the formation and growth of brittle O phase could be effectively inhibited. Through aging process, both strength and toughness of composites have achieved a remarkable enhancement. Tensile fracture strength and strain of composites were significantly improved by 87% and 74% respectively compared with TiAl matrix. The K_1C reflecting the toughness was enhanced nearly doubled benefit from multiple interaction mechanisms. The compressive strength of composites at 700 °C can reach 1078 MPa which still reached up to 847 MPa at 800 °C. The micromechanical properties of each phase were investigated systematically to reveal the strengthening and toughening mechanism. The growth behavior and the stability of interface structure were also involved with first-principles method.