Microstructure and mechanical properties of TiAl-based composites prepared by Stereolithography and gelcasting technologies

TiAl intermetallic and SiC ceramic are two kinds of important high-temperature structural material, but it is difficult to fabricate complex high-performance composites of them by traditional methods. In the paper, it is a pioneer study to prepare their composites so as to fabricate turbine blade by the hybrid technology of Stereolithography and gelcasting. Impregnation and pyrolysis behaviors of polycarbosilane were explored for SiC ceramic preparation, and the microstructure evolution and mechanical properties of TiAl-based composites were mainly analyzed. The results showed that adding trace amount of nickel and aluminum could remarkably promote the sintering of gelcasting TiAl intermetallic samples, the micropores inside TiAl samples were connected after debinding, and the metallurgical structures were all intermetallic. After the porous TiAl samples impregnated with polycarbosilane were then pyrolyzed three times, the final metallurgical structures were TiAl-based composites of TiAl, NiAl, SiC, TiC and Ti3SiC2. Ti3SiC2 was the interface layer formed between TiAl intermetallic and SiC ceramic, and their high-temperature bending strength was between 82 MPa and 90 MPa at 1100 °C. Therefore, it was a promising method for the fabrication of complex high-performance TiAl-based parts such as turbine blade.