Study on Properties of Carbon Fiber Reinforced Titanium Matrix Composites by Direct Ink Writing 3D Printing

Using direct-write 3D printing technology combined with hot-press sintering, oriented chopped carbon fiber-reinforced Ti6Al4V composites with carbon fiber content ranging from 0.3% to 0.9% were fabricated. The rheological behavior of the composite slurry and the effects of carbon fiber content on the microstructure and mechanical properties of the composites were systematically investigated. The results indicate that the viscosity and shear stress of the composite slurry decrease with increasing carbon fiber mass fraction. The carbon fibers achieve alignment along the printing direction within the extrusion shear field and react with the Ti matrix during hot-press sintering to form a TiC interfacial coating layer. Mechanical property tests indicate that as the carbon fiber content increases, both the tensile strength and yield strength of the composite exhibit a trend of first increasing and then decreasing, reaching a peak (565 MPa) at a content of 0.7%, while hardness continues to rise and the post-fracture elongation decreases monotonically. This performance evolution is attributed to a competitive mechanism between fiber-oriented reinforcement, TiC interfacial strengthening, and the proliferation of pore defects at high fiber contents. Fracture analysis confirms that the surface grooves formed by nitric acid etching, together with the reaction-generated TiC layer, constitute a dual interface reinforcement mechanism of “mechanical interlocking + chemical bonding,” ensuring effective load-bearing by the fibers.