Microstructure and properties of graphite nanoflakes/Cu matrix composites fabricated by pressureless sintering and subsequent thermo-mechanical treatment

摘要

A self-developed pressureless sintering and subsequent thermo-mechanical treatment process was employed to fabricate 1-5 wt% graphite nanoflakes (GNFs)/Cu matrix composites. The distribution of GNFs and GNFs/Cu interface structure, as well as mechanical and thermal properties of the composites were investigated. The results showed that the thermo-mechanical treatment can significantly improve the GNFs/Cu interface structure, as well as the densities and properties of the composites. However, the distribution orientation of the GNFs and the anisotropy of properties of the composites increase in the process. After pressureless sintering and thermo-mechanical treatment, the relative densities of the 1-5 wt% GNFs/Cu matrix composites can rise as high as 99.4%. As the amount of the GNFs is increased from 1 wt% to 5 wt%, the thermal conductivities of the composites change from 380.4 W/(m.K) to 244.4 W/(m.K) in rolling direction and from 179.3 W/(m.K) to 51.9 W/(m.K) in normal direction. The tensile strengths and the coefficients of thermal expansion of the composites change form 153 MPa to 56 MPa and from 13.5 x 10(-6)/K to 11.9 x 10(-6)/K respectively. This fully satisfies the application requirements of electronic packaging materials.