Effect of metal catalyst thermal expansion on thermal stability of synthetic diamonds

Thermal stability of synthetic diamonds grown in various metallic solutions in terms of their residual strength after thermal loading is studied. The micromechanical, cohesive zone model of crack initiation and propagation in the diamond crystal in a vicinity of metal inclusion has been developed. The inclusion–diamond thermal expansion mismatch is found to be a key factor responsible for the strength reduction of diamond crystals after high-temperature treatment. The results of computer simulation satisfactory correlate with the available experimental data.