Creation of Nanostuctures by Extreme Conditions: High-Pressure Synthesis of Ultrahard Nanocrystalline Cubic Boron Nitride



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The synthesis of high-purity bulk nanostructured cubic boron nitride (cBN) at 20 GPa and 1770 K by direct phase transformation of graphite-like BN with an “ideal random layer” structure is reported. The two-times increase of hardness of nano-cBN (HV = 85 GPa) with respect to conventional polycrystalline cBN (HV ∼ 45 GPa) is evidently a result of nanosize effects.