In situ synthesis of nano/micron Ti2AlC reinforced high-Nb TiAl composites: Microstructure and mechanical properties

Induction hot-pressing sintering, as an effective sintering technique, has been rarely investigated and reported in the sintering of TiAl alloys. In this paper, in-situ nano/micron Ti2AlC reinforced high-Nb TiAl composites were fabricated via induction hot-pressing sintering, and the effect of nano-C addition on the microstructure and tensile properties was investigated. With 0.75 at% nano-C addition, the lamellar colony size decreased from 406 +/- 151 mu m to 141 +/- 62 mu m, and the Ti2AlC particles were mainly distributed at the gamma/alpha 2 lamellar interface. At 800 degrees C and 900 degrees C, the ultimate tensile strength and the elongation of the TiAl alloy were 436 MPa and 437 MPa, 0.84%, and 1.12%, respectively. However, with 0.75 at% addition (after heat treatment 900 degrees C/48 h), the ul-timate tensile strength increases by 129 MPa and 78 MPa, and the elongation increases by 0.27% and 0.64%, respectively. The significant improvement in tensile property is mainly attributed to the precipitation phase enhancement and grain refinement.