Non-dislocation mechanisms of deformation localization in nickel nanocrystals in the process of high-pressure torsion in Bridgmen anvils
Investigation of the formation features of reorientation nanobands with the participation of non-dislocation deformation mechanisms: local invertible (FCC → BCC → FCC) martensitic-type transformations and quasi-viscous mass transfer by flows of nonequilibrium point defects in fields of high local pressure gradients, was conducted using the methods of transmission electron microscopy in nickel nanocrystals under conditions of severe plastic deformation by torsion in Bridgman anvils. The features of the disclination structure and the elastic-stress state at the nanobands propagation front were studied. Theoretical analysis of the rate of plastic deformation by mechanisms of quasi-viscous mass transfer by flows of non-equilibrium point defects was conducted. The possibility of the simultaneous realization of martensitic and quasi-viscous deformation modes at the nanobands propagation front is shown.Based on these results, the analysis of conditions and mechanisms for the realization of martensitic and quasi-viscous deformation modes depending on point defects type (vacancies and interstitial atoms), deformation temperature, features of disclination structure and elastic-stress state at nanobands propagation front was conducted.