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Abstract

Plastic deformation of metals is a complicated phenomenon that links behaviour of crystal defects with macroscopic change of a sample shape. It is known that the basic mechanism of plasticity is a motion of dislocations under applied stress. In this work, on the example of Mo and Nb, the study of plastic deformation in bcc metals was performed with multi-scale modelling. The temperature-dependent mobility functions of screw and edge dislocations were calculated from molecular dynamics simulation. The simulations of screw dislocation movement under applied shear stress revealed that the process can proceed in two different regimes: through thermally activated motion and athermal motion. Hence, the dislocation velocity depends on the shear stress in a non-trivial way. The calculated data were implemented in the dislocation dynamics model. Such model allows to simulate plastic deformation taking into account temperature effect on the dislocation mobility. The changes of yield stress predicted by the dislocation dynamics simulation at variation of input parameters are analysed in details.