Microstructural evolution and electro-resistivity in HPT nickel

Microstructural evolution of pure nickel was studied in the very early stages of high-pressure torsioning. It is shown that the microhardness becomes sufficiently homogeneous across the disks after one-half of a complete revolution. An analysis by EBSD supports this finding showing almost identical EBSD microstructures for HPT through more than 0.5 rotation. Electrical resistivity measurements correlate with the microhardness and EBSD data showing a maximum value at the strain corresponding to 0.5 rotation. The results suggest that the main source of electron scattering is point defects and dislocations.