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

Several nanostructured states of high purity cobalt were achieved by highpressure 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 resultof HPT and subsequent annealing have been measured and analyzed. Mechanicalproperties of nanostructured Co were studied by microhardness measurements at300 K, and uniaxial compression at temperatures 300, 77 and 4.2 K. Comparison ofthe strength characteristics, plasticity and strain hardening of the nanostructured andcoarse grained Co has been carried out. Micromechanisms of plastic deformation of Coduring HPT deformation and uniaxial compression are discussed