In this work, we prepared titanium matrix composites (TMCs) reinforced with in-situ polycarbosilane (PCS)derived TiC particles. The effects of PCS addition on the microstructure, interface, hardness, and tribological properties were studied. The pyrolysis of PCS leads to the formation of in-situ TiC particles and Si solid-solution at a low PCS content (<= 3 wt%). The TiC particles with a particle size of 4.8 mu m are uniformly distributed in TMCs and have a well-bonded interface with the Ti matrix. The average grain size of alpha-Ti decreases from 100.5 mu m in pure Ti to 16.1 mu m in the Ti-3 wt% PCS composite. The presence of in situ synthesized TiC particles contributes to the excellent wear resistance of the Ti/PCS composites, which is ascribed to the increased hardness, superior load transfer capability, and oxidation wear resistance. The Ti-3 wt% PCS composite possesses the hardness of 4.72 GPa, elastic modulus of 169.23 GPa, and a low specific wear rate of 0.84 x 10(-12) m(3)/(N.m) under constant conditions (3 N, 0.03 m/s). These values are all superior to those of Ti-6Al-4V alloy. This work sheds light on the design of high wear-resistant TMCs for industrial applications.

In this work, we developed a powder conditioning process that involves coating polycarbosilane (PCS) on Ti particles. After sintering, the conditioned Ti powder was converted into Ti composites. TiC was derived from the pyrolysis of PCS and forming an in-situ reinforcement. There exists a specific orientation relationship of (111)(TiC )parallel to(10 (1) over bar0)(Ti); and [11 (2) over bar](TiC)parallel to[1 (2) over bar 10](Ti). The average grain size of alpha-Ti decreases significantly from 100.5 mu m in pure Ti to 16.1 mu m in the Ti-3 wt.% PCS composite. When the PCS content is 4 wt%, Ti3Si particles precipitate out, and they are combined with TiC forming an aggregated network architecture. Among these Ti composites, the 3 wt% PCS sample exhibits a high tensile strength of 861 MPa, high yield strength of 754 MPa and reasonably large elongation of 10.8%, respectively.

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.