In situ formation of low interstitials Ti-TiC composites by gas-solid reaction

Abstract

In this work, in situ formation of low interstitials Ti-TiC composites with a high relative density has been fabricated by the combination of TiH2-CH4 reaction and vacuum pressure-less sintering. During the gas-solid reaction, TiH2 reacted with CH4 to form TiC particles on the powder surface. As a consequence, low interstitials contents (O < 0.21 wt%, N < 0.062 wt%, H < 0.011 wt%) were obtained in as-sintered materials. TiC particles uniformly distributed in the Ti matrix with a particle size of 3–12 μm, resulting in the grain refinement from 87.89 μm to 34.76 μm. The as-sintered Ti-35 vol%TiC exhibited high tensile strength of 644 MPa in YS and 736 MPa in UTS. Considering about ductility, the Ti-15 vol%TiC obtained comprehensive mechanical properties, about 628 MPa in YS, 715 MPa in UTS and 12.1% in elongation. The acceptable ductility (elongation > 10%) is important for following thermomechanical processing. In summary, the achievement of high performance Ti-TiC composites was attributed to the grain refinement, in-situ TiC strengthening, as well as a solid solution strengthening of the O, N and C elements in the Ti matrix.