Diamond anisotropic surface transformation and its effect on the interfacial microstructure of al/diamond composites

Abstract In this study, Al/diamond high-conductive metal matrix composites were fabricated using the gas pressure infiltration (GPI) method with different times of heat preservation to study the surface microstructure transition and its effect on the interface of composites. The results show that during the fabrication of Al/diamond composites, phase transformation from diamond structure to amorphous structure and the graphitization would happen on the diamond surface. On the different planes of the diamond surface, including {100} and {111}, the phase transition happens differently, which is strongly influenced by the initial state fabricating temperature and time. This difference determines the diffusive reaction between the molten aluminum and diamond particle during the process and has a significant effect on the growth and shape of aluminum carbide. As a result, the interface of GPI Al/diamond composites performs the anisotropic characteristic. Therefore, proactive treatment of diamond particles and fabrication of composites have to be critically controlled and optimized to obtain the ideal combination of anisotropic {100} and {111} interface enhancing and stabilizing the thermal conductivity and coefficient of thermal expansion.