Influence of W content on the microstructural evolution and mechanical properties of (TiZrHfNbTaW )C multi-component carbides

The (TiZrHfNbTaW x )C ceramics with varying W contents were fabricated via carbothermal reduction and spark plasma sintering (SPS). The influence of sintering temperature on the solid solution process and the effect of W content on the microstructure and mechanical properties were investigated. Under the sintering condition of 1700°C, although a single phase is formed, the elemental distribution remains non-uniform, indicating that the solid solution process is still incomplete. At 1800°C, a single phase with homogeneous elemental distribution is achieved. Meanwhile, with the W content increasing, the relative density rises while accompanied by grain coarsening. This phenomenon may be attributed to enhanced lattice distortion promoting grain boundary migration and the higher diffusion coefficient of W. At lower W contents (4.76 at%), superior mechanical properties are obtained due to finer grain size, achieving a flexural strength of 649 MPa, fracture toughness of 3.45 MPa·m 1/2 and Vickers hardness of 21 GPa. At higher W contents, although the hardness slightly improves, the enhancement is marginal due to larger grain size, furthermore, the fracture mode shifts from predominantly intergranular to transgranular fracture.