Effect of dynamical heating on microstructure and microhardness of Ni processed by high-pressure torsion

The microstructures and microhardness of pure Ni processed by high-pressure torsion and their evolution upon dynamical heating from room temperature to 200 °C at a heating rate of 20 °C/min were investigated. The annealing resulted in further refinement of grains, formation of more fraction of high-angle grain boundaries (GBs), modification of state of GBs and ordering of dislocations. As a result of the microstructural optimization, the microhardness of the material was increased but not decreased after the dynamical heating.