Structure evolution in copper during powders consolidation by high pressure torsion

Abstract

The structure peculiarities of nanocrystalline copper produced by cryogenic milling and high pressure torsion (HPT) were studied. Special attention was paid to mechanisms of grain growth in nanocrystalline copper during HPT. It was established that at high strain degrees equiaxed nanocrystalline structure with the average size about 100 nm and dislocation density in powder copper ?2?1015 m–2 forms in powder copper, which is the result of dynamic equilibrium between the processes of dislocation pile-up and refinement of grain structure on the one hand, and annihilation of dislocations and grain growth on the other hand.