researchers have been able to push WB2 into the superhard regime through minority additions of other transition metals such as niobium and tantalum in the crystal structure. This mechanism of hardness enhancement is called solid solution strengthening and arises because atoms of different sizes are incorporated into the parent lattice to impede dislocation motion. Aluminium magnesium boride Aluminium magnesium boride or BAM is a chemical compound of aluminium, magnesium and boron. Whereas its nominal formula is AlMgB14, the chemical composition is closer to Al0.75Mg0.75B14. It is a ceramic alloy that is highly resistive to wear and has a low coefficient of sliding friction. Other boron-rich superhard materials Other hard boron-rich compounds include B4C and B6O. Amorphous a-B4C has a hardness of about 50 GPa, which is in the range of superhardness. It can be looked at as consisting of boron icosahedra-like crystals embedded in an amorphous medium. However, when studying the crystalline form of B4C, the hardness is only about 30 GPa. This crystalline form has the same stoichiometry as B13C3, which consists of boron icosahedra connected by boron and carbon atoms. Boron suboxide (B6O) has a hardness of about 35 GPa. Its structure contains eight B12 icosahedra units, which are sitting at the vertices of a rhombohedral unit cell. There are two oxygen atoms located along the (111) rhombohedral direction. Nanostructured superhard materials Nanosuperhard materials fall into the extrinsic category of superhard materials. Because molecular defects affect the superhard properties of bulk materials it is obvious that the microstructure of superhard materials give the materials their unique properties. Focus on synthesizing nano superhard materials is around minimizing microcracks occurring within the structure through grain boundary hardening. The elimination of microcracks can strengthen the material by 3 to 7 times its original strength. Grain boundary strengthening is described by the Hall-Petch equation Here σc is the critical fracture stress, d the crystallite size and σ0 and kgb are constants. If a material is brittle its strength depends mainly on the resistance to forming microcracks. The critical stress which causes the growth of a microcrack of size a0 is given by a general formula Here E is the Young's modulus, kcrack is a constant dependent on the nature and shape of the microcrack and the stress applied and γs the surface cohesive energy. The average hardness of a material decreases with d (crystallite size) decreasing below 10 nm. There have been