Effect of Hot-forging Temperature on the Microstructure and Thermal Conductivity of Copper/W-coated Diamond Composites

Copper/diamond composites have been proposed as thermal management materials for high performance electronic devices. However, their thermal conductivity (TC) is limited by the weak interfacial bond between the copper and the diamond, due to their poor chemical affinity. To enhance the TC, tungsten (W) was explored as an effective element, reacting with diamond to form a tungsten carbide interface between copper and diamond. This study involved fabricating copper/55vol%W-coated diamond composites via hot forging at temperatures of 800 °C, 950 °C, and 1050 °C. Additionally, annealing of W-coated diamond particles at these temperatures was also conducted to investigate the tungsten carbide interface formation mechanisms on diamond surfaces. The results of the hot-forged composites revealed that the TC of these composites initially increased with rising temperature but then decreased, correlating with distinct phase compositions and interface morphology formed at different hot-forging temperature. Analysis of the annealed W-coated diamond particles found that the reaction temperature for tungstencarbon to form tungsten carbide was above 950 °C, and inner stress at the interface could also contribute to the formation of tungsten carbide during the hot-forging process. Consequently, the optimal interface primarily composed of WC phase with a minor W2C phase was obtained in 950 °C hot-forged copper/55vol%W-coated diamond composite, and the resultant composite had the highest TC of 432 W/mK. This study offers valuable insights into tungsten carbide interface formation at varying temperatures in copper/W-coated diamond composites, aiding in the selection of the fabrication parameters for future studies.