In the present work, microcrystals of synthetic diamond extracted from a metal-diamond composite were investigated. A composite based on Cu and Fe was obtained by sintering at a pressure of 4 GPa and a temperature of1300 °C. The experiments were carried out using a split-sphere high-pressure apparatus BARS. The high-pressure cell was made of refractory oxides ZrO2, CaO, and MgO using a tubular graphite heater. In the composite, diamond grains were in close contact with neighboring diamonds, and the metal phase filled the interstices. The study of the diamond crystals demonstrated the appearance of newly formed micromorphological structures on the surfaces in the form of numerous cavities of irregular shape on the faces of octahedron, as well as pyramids on the faces of cube, the morphological elements of which follow the contours of the cube face of the diamond. Thus, the results of the work evidence for the processes of etching of the diamond crystals during the experiments, which is associated with the presence of metallic iron in the composite. This type of etching forms a roughly cavernous surface on the diamond crystals, which can be considered as an additional factor for improving the metal-diamond bond in copper-based composites.
Synthesis of gem diamond crystals by multiseed method using China-type cubic high-pressure apparatus