Nonequilibrium Diamond Growth during the High-Temperature High-Pressure Synthesis of a Composite Material Made of a Mixture of Cobalt and Fullerene Powders

A composite material (CM) reinforced by diamond particles is fabricated from a mixture of cobalt and 10 wt % C60 powders at a pressure of 8 GPa and a temperature of 1200–1300°C, which is close to the melting temperature of the metastable Co–C eutectic. The results of X-ray diffraction, Raman spectroscopy, and electron-probe microanalysis demonstrate that the CM consists of diamond and the Co3C carbide. Diamond crystals are shown to grow as plates parallel to a {100} plane according to the mechanism of nonequilibrium normal growth during liquid-phase CM synthesis. The diamond particles have a hardness of 82 GPa at an elastic recovery of 95%. The structure of the synthesized cobalt-based CM with diamond inclusions ensures its ultrahigh wear resistance and antifriction properties.