Influence of Cr Addition on the Microstructure and Mechanical Properties of WCoB–TiC Ceramic Composites

In this study, the mechanical and electronic properties of W₂CoB₂ hard phases in the WCoB–TiC ceramic composites with varying Cr contents were analyzed using first-principles calculations. Experimental measurement was conducted to determine the microstructure, hardness, transverse rupture strength (TRS), and fracture toughness (K_Ic) of WCoB–TiC ceramic composites with different Cr contents. First-principles calculations showed that adding a small amount of Cr could increase the bulk elastic modulus of the material. However, as the concentration of Cr increased, its bulk elastic modulus decreased. Moreover, it was found that Cr doping effectively enhanced the material's toughness, which might be attributed to strengthening the covalent bond property of the B–Cr chemical bond with higher Cr doping concentrations. The experimental results indicated that Cr doping reduced the density of Cubatic ceramic composites. Still, a small amount of Cr could refine the grain size of the hard phases, thereby enhancing the overall mechanical properties of the composites. The WCoB–TiC ceramic composites achieved the highest hardness, TRS, and K_Ic values of 92.3 HRA, 906.5 MPa, and 12.45 MPa ∙ m^1/2, respectively, at a Cr content of 2.0 wt.%.