Solubility and stability of diamond in cobalt under 5 GPa

The stability and solubility of diamond in cobalt at a pressure of 5 GPa was investigated. At temperatures ranging from 1000 °C and 1350 °C, diamond can be dissolved in cobalt without graphitization . Meanwhile, the solubility of single diamond crystals in cobalt was measured at 5 GPa and temperatures of up to 1300 °C through weight analysis, and it was found to increase with the increase in temperature. The morphological changes of the diamond crystals after high-pressure and high-temperature (HPHT) treatments were observed using a scanning electron microscope . The resulting quantitative data and morphology analysis enabled the construction of a scheme for the morphological evolution of diamond crystals during their dissolution in cobalt at HPHT. The diamond formation process in cobalt solvent is discussed in relation to the dynamic equilibrium.