Mechanical properties of superhard boron subnitride B13N2

Microstructure and mechanical properties of bulk polycristalline rhombohedral boron subnitride B13N2 synthesized by crystallization from the B-BN melt at 7 GPa have been systematically studied by micro- and nanoindentation, atomic force microscopy and scanning electron microscopy. The obtained data on hardness, elastic properties and fracture toughness clearly indicate that B13N2 belongs to a family of superhard phases and can be considered as a promising superabrasive or binder for cubic boron nitride.