Correlation of structure development and electric characteristics within high pressure torsion processed copper Korrelation zwischen Mikrostrukturentwicklung und elektrischen Eigenschaften von durch Hochdruck-Torsion verarbeitetes Kupfer

Abstract

Copper of a high purity features excellent electric conductivity, but generally very low mechanical properties. Nevertheless, optimized deformation/thermomechanical treatment can introduce favorable combinations of both. The presented study characterizes the correlation of microstructure development and electric properties within copper processed by the severe plastic deformation method of high pressure torsion, the primary advantage of which is that it enables to achieve grains with the sizes in the ultra-fine, or even nano scales. The study investigates structure development during progressive deformation. In other words, samples processed by single and double high pressure torsion revolutions were evaluated from the viewpoints of grain sizes and grain boundaries, and the results were correlated with the experimentally measured electric conductivity. The single high pressure torsion revolution contributed to grain size decrease, while the structure after double revolution exhibited very fine grains, especially at the sample periphery featuring the highest imposed strain. Both the samples also exhibited increases in microhardness (especially after double revolution), and electric conductivity higher than 100 % IACS. The results confirmed that copper conductors featuring enhanced mechanical properties and favorable electric conductivity can be manufactured by severe plastic deformation.