Deformation characteristics at the Cu-Al contact surface during hydrostatic extrusion of a biaxial Cu-Al bar

This work is concerned with the deformation behaviours at the Cu-Al contact surface during hydrostatic extrusion of a concentric Cu and Al bar. In general, the unavoidable oxidisation at the Cu-Al contact surface prevents the bonding at the Cu-Al contact. A ‘local extrusion’, defined as a material flow through a fractured and expanded oxidised layer, is necessary for the successful bonding at the Cu-Al contact in a post process. Experiments consisting of extrusion and sintering with a biaxial Cu-Al bar are performed and it is confirmed that a ‘local extrusion’ does occur. In finite element studies, focuses are given to the behaviours of the first principal strain and the stress component normal to the Cu-Al contact profile since they are essential parameters for the success of a ‘local extrusion’. In this work, half die angle and extrusion ratio are considered as the most important process parameters. Effects of such process parameters on the deformation characteristics at the Cu-Al contact surfaces during hydrostatic extrusion are carefully examined.