T. Schubert, H. Weidmüller, Fraunhofer Institute for Manufacturing Technology and Applied Materials
Research, Dresden (Germany); T. Weißgärber (Sp), B. Kieback, Fraunhofer Institute for Manufacturing
Technology and Applied Materials Research, Dresden (Germany)
Metal matrix composites were produced with the aim of obtaining high thermal conductivities for thermal
management applications by reinforcing copper-alloys with natural graphite flakes or diamond single crystals via
powder metallurgy.
The produced composites exhibit thermal conductivities in the range of 400 W/mK to 600 W/mK combined with a
reduced thermal expansion. It was revealed, that a local carbide formation can promote the interfacial bonding
between reinforcement and copper, and therefore improves the bulk thermal properties of the composites. A
strong anisotropy of the properties in case of the copper-graphite composites must be considered unlike the
diamond reinforced copper. The pressing conditions during fabrication seems to vary the thermal conductivity by
modification of the microstructural characteristics of the interfaces. The copper composites with good interfacial
bonding show only small decrease in thermal conductivity and a relatively stable CTE after the thermal cycling
test.