Small tungsten carbide nanoparticles: Simulation of structure, energetics, and tensile strength

Ab initio methods of the density functional theory and pseudopotentials were used to study the structure, electronic states, total energy and tensile strength of WC nanoparticles. It has been found that the very small particles (having less than 15 WC atomic pairs) have a cube-like NaCl structure. Particles with trigonal and cubic structures have approximately the same energies in the region of 10–20 WC pairs; however, the local atomic structure keeps the NaCl-like alternation of W and C atoms. The WC15 trigonal particle was used as a typical one to study the WC nanoparticle tensile strength. It has been found that W and C vacancies decrease the tensile strength, but not drastically. Electronic structure of nanoparticles looks like that of bulk fcc-WC with a large density of states at the Fermi level.