HPHT Crystallization of Diamond on Seed with Use of Carbon Solvents Prepared by Powder Metallurgy Methods

Thermobaric formation of carbon solvent alloys under high pressures of 4–6 GPa and at temperatures of 1200–1300°C is used to grow structurally perfect diamond single crystals in the region of thermodynamic stability. It is shown that the formation of samples with minimum values of porosity in the range from 2.49 to 4.50% ensures a stable distribution of elements over the growth volume even in the presence of large differences in the density of elements. For comparison, the results of experiments on the formation of solvent alloys by the methods of powder metallurgy and direct isostatic pressing with subsequent sintering and by the methods of hot pressing of powders are given. It is shown that the samples obtained by classical methods have relatively large final porosity values and cannot be used in the future as carbon solvent alloys during directed growth of diamond single crystals at high pressures and temperatures.