Enhancement of diffusion bonding of silver graphite to copper by severe plastic deformation

The conventional press and sinter (CPS) method for fabrication of bi-layered silver graphite-copper electrical contacts has shown to be challenging process due to the immiscibility of graphite in copper and silver. In this work, severe plastic deformation (SPD) by equal channel angular processing (tCAP) has been used to enhance diffusion bonding and interface properties of bi-layered silver graphite-copper. Both, electron backscatter diffraction (tBSD) and energy dispersive X-ray spectroscopy (tDS) measurements have verified that through tCAP processing, the interface is free of the detrimental graphite deposits. This is attributed to presence of high density of lattice defects, such as high energy and high mobility grain boundaries. These defects have low activation energy, and tend to enhance diffusion.