Effect of hot forging temperature and diamond volume fraction on TiC interface evolution and thermal conductivity of hot-forged Ti-coated diamond/Cu composites

Abstract

Diamond/Cu composites are developed as a solution to the challenge of dissipating heat in electronic devices, due to the potential to have a high thermal conductivity (TC) and a coefficient of thermal expansion (CTE) close to that of the electronic devices. In this study, Ti-coated diamond/Cu composites were fabricated by hot forging. Fabrication parameters were manipulated by altering the volume fraction of diamond and adjusting the hot forging temperature to determine the optimal combination of parameters to produce Ti-coated diamond/Cu composites with high TC. The microstructure of the hot-forged composites and the interface characteristics were characterized by SEM, and the interfacial bond strength between the copper and the diamond was assessed based on tensile test results. Compared to other fabrication temperatures of 700 °C and 850 °C, 800 °C is the optimal hot forging temperature to facilitate the dynamic formation of TiC interface layer and ensure a high interface coverage rate on the diamond particles. Additionally, the volume fraction of diamond affects the interface microstructure and TC of the hot-forged composites by affecting the heating behaviour of the composites during induction heating. As a result, 800 °C hot-forged composites with a composition of 45vol%Ti-coated diamond achieved the highest TC (455 W/mK) among the fabricated composites and exhibited good ductility at a high tensile strength of 124 MPa. The findings indicate that the high TC of the Ti-coated diamond/Cu composites are ensured by the synergy of uniform distribution of diamond in the matrix, a rough interface, and strong interfacial bonding between the copper and the diamond. This paper provides insights into the TiC interface formation mechanisms occurring during the induction heating and hot forging fabrication process.