Microstructure and Mechanical Properties of Carbon/Carbon Composites Infiltrated with Ti–6Al–4V Titanium Alloy

In this work, chemical vapor infiltration (CVI) was combined with reactive melt infiltration (RMI) using Ti–6Al–4V titanium alloy powder to prepare Cf/C–TiC composites. The microstructure and composition of Cf/C–TiC composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The flexural properties of the composites were also analyzed. The results indicated that the Ti–6Al–4V titanium alloy infiltrated the Cf/C preform and reacted with the pyrolytic carbon (PyC) to form a TiC–VC and Al4C3 matrix, and no residual Ti, Al, or V was detected. Moreover, Al4C3 was concentrated and independently distributed, whereas Ti and V reacted with C to form a TiC–VC solid solution. The porosity was 6.75%, and the bulk density of Cf/C–TiC was 1.96 g/cm3. The flexural strength, flexural modulus, and failure strains were 256 ± 18 MPa, 89 ± 9 GPa, and 0.93 ± 0.13%, respectively. The work of fracture of the Cf/C–TiC composite was about 6.8 ± 0.38 KJ/m2. Due to the propagation and deflection of cracks, as well as debonding and fiber pullout, the Cf/C–TiC composite showed ductile fracture behavior.