The Change of Metal Inclusions and Its Influence on the Strength of Synthetic Diamond

At a temperature of about 1 000 ℃, larger defect areas in the crystal lattice of synthetic diamond will be formed with changes in the shape, in the composition and in the structure of metal inclusion. So it is the basic cause of the strength loss of synthetic diamonds heated at high temperatures. The size of defect areas increases with changes above. To a series of synthetic diamond samples-heated at different temperatures and in argon atmosphere, strength values have been measured. All the results supported the conclusion above. It was also supported that the heating stability of synthetic diamond is strongly influenced by metal inclusions which make it easier for diamond to return to graphite at a lower temperature of about 1 000 ℃.