金属包裹体的变化及对人造金刚石强度的影响

 当温度超过1 000 ℃时，人造金刚石中的金属触媒包裹体，在形态、结构和成份上都将发生改变，并且这种变化会在金刚石晶格内造成尺寸更大的缺陷区域，因此在表面氧化不起决定性作用的情况下，金属触媒包裹体的这种变化，就成了导致金刚石强度下降的最直接的原因。我们对在氩气保护下、不同温度处理的一系列人造金刚石样品进行了强度测量，并用SEM、X射线衍射及光学显微镜等手段观测了金刚石断裂表面上的包裹体及其形态变化。我们的实验结果证实了上述结论。我们还发现，金属触媒包裹体的存在极大地影响着金刚石的热稳定性，它们使金刚石在1 000 ℃左右即可向石墨转化。

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 ℃.