Indentation contact behavior of copper–graphite particulate composites: Correlation between the contact parameters and the electrical resistivity

The elastoplastic contact surface deformations of copper–graphite particulate composites are examined in instrumented Vickers/spherical indentation tests. The composites include various contents of metallic Cu-particles with various sizes and shapes originated from the starting powders, that are mixed with flaky natural graphite having various sizes. The elastoplastic surface deformations of the composites are characterized in term of the elastic modulus E′, contact hardness H, and the relative residual depth ξr of hardness impression. The surface deformations of the composites are well correlated to their microstructures and electrical resistivities. It is concluded that the evolution of the percolation structures of Cu-phases is essential in controlling the electrical resistivity and the plastic ductility of the composite.