Electron Microscopy of Diamond Synthesized by Explosive Shock

The microstructure of early shock-synthesized diamond was discussed in a previous report; this paper is concerned with the characterization of improved material which is now available from E. I. du Pont de Nemours & Company in various size ranges suitable for lapping and polishing.This new type of synthetic industrial diamond is produced by shocking dense graphite-metal mixtures at high explosive pressures. It consists of two types of particles which are shown in Figure 1; polycrystalline aggregates which are rounded and have a mottled surface, and single crystals or fragments thereof which have straight edges and flat surfaces. Figure 2 shows the two types of particles in transmission; they both partly consist of the hexagonal modification of diamond. Single crystals have either a cubic or a hexagonal habit and they often contain large numbers of stacking faults. Polycrystalline particles consist of densely aggregated bundles of acicular crystallites having an average width of 150 A and a length varying between 0.05 and 0.3 p.; a strong preferred orientation is invariably present (Figure 3).