Diffusion-controlled alloying of single-phase multi-principal transition metal carbides with high toughness and low thermal diffusivity

Multicomponent alloying has displayed extraordinary potential for producing exceptional structural and functional materials. However, the synthesis of single-phase, multi-principal covalent compounds remains a challenge. Here, we present a diffusion-controlled alloying strategy for the realization of covalent multi-principal transition metal carbides (MPTMCs) with a single face-centered cubic phase. The increased interfacial diffusion promoted by the addition of a nonstoichiometric compound leads to rapid formation of the single phase at much lower sintering temperature. Direct atomic-level observations via scanning transmission electron microscopy demonstrate that MPTMCs are composed of a single phase with a random distribution of all cations, which holds the key to the unique combinations of improved fracture toughness, superior Vickers hardness, and extremely lower thermal diffusivity achieved in MPTMCs. The present discovery provides a promising approach toward the design and synthesis of next-generation high-performance materials.