Abstract:Metal/diamond composites with excellent thermal and mechanical properties are promising materials for thermal management applications, but the weak interfacial bonding between metals and diamond restricts industrialization processing. In this study, first-principle calculations based on density functional theory were employed, focusing on the (111) planes of three face-centered cubic (FCC) metals (Al, Cu, and Ag) and the (111) plane of diamond. A series of Cr-doped interface models with a concentration gradient of 12.5%~62.5% were constructed to systematically investigate the regulatory effect of Cr doping on interfacial bonding performance. Combined with calculations of surface relaxation, surface energy, and interfacial adhesion work, as well as analyses of charge density difference and partial density of states (PDOS), the microscopic mechanism of interfacial strengthening was revealed. Results showed that Cr doping exhibited a significant strengthening effect on Cu/diamond and Ag/diamond interfaces: adhesion work presented a distinct increasing trend with the rise of doping concentration, reaching 0.265 J/m2 and 0.254 J/m2, respectively, at a concentration of 62.5%, both significantly higher than those at 12.5% concentration. In contrast, due to the strong intrinsic Al-C polar covalent bonds and saturated electronic structure at the Al/diamond interface, Cr doping only slightly improved adhesion work to 0.293 J/m2, showing low sensitivity to concentration changes. Analysis of interfacial electronic structure confirmed that introduction of Cr can form stable Cr-C covalent bonds through strong hybridization between Cr-3d orbit and C-2p orbit, thereby reconstructing interfacial electronic structure. However, Al formed saturated covalent bonds with C, making it difficult for Cr to participate in effective hybridization. This study provided an important theoretical basis for optimization interfacial design of metal/diamond composite materials and offered guiding significance for promoting their applications in fields such as thermal management.