Two-scale simulation of plasticity in molybdenum: Combination of atomistic simulation and dislocation dynamics with non-linear mobility function
S Starikov and V Tseplyaev, COMPUTATIONAL MATERIALS SCIENCE, 179, 109585 (2020).
We present multi-scale simulation of plastic deformation in molybdenum. The temperature-dependent mobility functions of screw and edge dislocations were calculated from molecular dynamics simulation with two different interatomic potentials. 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. We took this fact into account during calculation of the mobility functions and their implementation in the dislocation dynamics (DD) model. Such model allows us to simulate plastic deformation with consideration of temperature effect on the dislocation mobility. Here we discuss the changes in DD predictions depending on the input parameters obtained from the atomistic simulation. As the main result, we report the yield stress calculated for a single crystal of molybdenum at various temperatures, strain rates, and dislocation densities. Thoroughly discussed comparison of the simulation results with the available experimental data gives opportunity to estimate the accuracy of the created multi-scale model.
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