Microstructure and Mechanical Properties of Polycarbosilane In-situ Reinforced Titanium Matrix Composites

The in-situ reinforced titanium matrix composites were fabricated using low-oxygen hydride-dehydride (HDH) Ti powders and polycarbosilane (PCS) via a powder metallurgy method, including solution-assisted wet mixing and pressureless sintering. The effects of PCS addition on the oxygen inhibition, sintering densification, microstructure and mechanical properties of the composites were investigated. The results show that the solution-assisted wet mixing process makes the Ti powders coated with PCS, which can effectively control the oxygen contamination. The oxygen content of the fabricated Ti-1.0% PCS (mass fraction) composite is 0.21%similar to 0.24%, much lower than 0.36%similar to 0.41% of CP-Ti. During sintering, the pyrolysis products of PCS can react with Ti matrix to in-situ synthesize TiC particles, while Si element is dissolved in matrix. The incorporation of PCS can improve the mechanical properties of the Ti matrix. The Ti-1.0% PCS composite sintered at 1200 degrees C for 2 h possesses the best mechanical properties, with a relative density of 98.4%, a Rockwell hardness of 37.1 HRC, a yield strength of 544 MPa, an ultimate tensile strength of 650 MPa, and an elongation of 14.5%. Therefore, the composite is obviously superior to CP-Ti in comprehensive performance index.