Deformation Induced Percolating Porosity in High Pressure Torsioned (HPT) Copper

Copper of different purity levels (4N, 5N) produced by High Pressure Torsion (HPT) with varying processing parameters is investigated utilizing the radiotracer technique. While the degree of deformation is constant, the effect of the applied quasi-hydrostatic pressure and of the impurity concentration on the as deformed samples is analysed. By applying the radio tracer method micro structural aspects are revealed that are not easily accessible by conventional methods. The measurements indicate the formation of a percolating porosity during the HPT process as a function of the applied pressure and (although less pronounced) of the impurity concentration.