Structure and properties of nanostructured cobalt processed by high pressure torsion at temperatures of 300 and 77 K

Abstract

Several nanostructured states of high purity cobalt were achieved by high pressure torsion (HPT) at pressures of 4 and 8 GPa and temperatures of 300 and 77 K. Changes of crystallographic texture, grain sizes and phase transformations as a result of HPT and subsequent annealing have been measured and analyzed. Mechanical properties of nanostructured Co were studied by microhardness measurements at 300 K, and uniaxial compression at temperatures 300, 77 and 4.2 K. Comparison of the strength characteristics, plasticity and strain hardening of the nanostructured and coarse grained Co has been carried out. Micromechanisms of plastic deformation of Co during HPT deformation and uniaxial compression are discussed. © Published under licence by IOP Publishing Ltd.