The synthesis of metal-matrix composite materials reinforced with superelastic hard carbon particles formed from C60 fullerites includes heating of the metal-fullerite powder mixture to temperatures above 800C under pressure. The structure evolution of the carbon particles upon heating from 700 to 800 C at a pressure of 5 GPa has been studied in detail by Raman spectroscopy and indentation hardness measurements. It is shown that the structure of the carbon particle passes the stage of a nanoscale mixture of one- and two-dimensional polymers with the resulting atomic superelastic solid phase. The determining properties of the carbon particles such as superplasticity and high hardness are attained before the complete disappearance of polymerized fullerites, the remnants of which are responsible for the disintegration of the material upon scratching.