A new route to fabricate dual-phase compositionally complex ceramics

A new route to fabricate dual-phase compositionally complex ceramics (CCCs) has been proposed, involving in-situ reactions and solid solution processes among various transition metals and B₄C by spark plasma sintering at 2200 °C for 10 min. Microstructural analysis reveals the presence of negligible porosity, fine grain size, and plate-like diboride grains in different systems. Element distribution within the phases is found to be non-uniform: Ti and V are enriched in the diboride phase, while Ta is preferentially dissolved into the carbide phase. Moreover, the tendency of Nb and Zr to dissolve into either the diboride or carbide phase is influenced by the introduction of new transition metal elements. Among these dual-phase CCCs, the Ti-Zr-V-Nb system exhibits exceptional comprehensive mechanical properties, including a fracture toughness of 5.5±0.3 MPa·m^1/2, Vickers hardness of 24.4±0.8 GPa, and flexural strength of 554±27 MPa, which surpass most of diboride and carbide dual-phase ceramics in the previous reports.