Simulation of uniaxial deformation of magnesium nanocrystals of “rigid” and “soft” orientations

Atomistic simulation of high-rate deformation ($v$ = 3 $\cdot$ 10$^{8}$ s$^{-1}$) by compressing perfect and defect (5% of vacancies and 5% of hydrogen impurity atoms) magnesium nanocrystals of “rigid” [0001] and “soft” [1$\bar1$01] orientations is performed at $T$ = 300–375 K using three different interatomic interaction potentials. The free surface microrelief evolution of magnesium nanocrystals during plastic flow is shown. Stress $\sigma$–strain $\varepsilon$ diagrams are constructed. The strain dependences of the scalar dislocation density are determined; the dependences of the strain rate $\dot{\varepsilon}$ on the strain measure $\varepsilon$ are constructed. The potential energy variation during deformation is considered. The formation of barriers causing the anomalous behavior of the strain rate is discussed. The effect of vacancies and hydrogen atoms on the shape of stress–strain curves, dislocation structure, and scalar dislocation density is shown. Conclusions about the effect of the type of the interatomic interaction potential on calculated characteristics are made.