After the strength of the samples has been tested, the micro structure and the content of the metallic carbonides at the diamond interface are observed and analyzed under the high power electron microscope and spectrometer. The strength order of the metallic carbonides generated in diamonds of different concentrations and sizes with different additives are calculated; hence the difference of the physical and mechanical properties of different metallic carbonides are determined, which provides the theoretical basis for the production and development of diamond products.