Dislocation Damping and Defect Friction Damping in Magnesium: Molecular Dynamics Study

In this study, the molecular dynamics method was used to study the damping mechanism in Mg alloys at the atomic scale. The energy dissipated by the nucleation and motion of dislocations and by defects friction, and the effect of defects, such as vacancies, cracks, and grain boundaries, on them were studied. The study shows that different kinds of defect have different effects on the dislocation damping and defect friction damping. And then, the effect of strain amplitude and temperature on damping capacity of Mg was studied. The result shows that the amplitude independent damping is caused by defect friction and the amplitude dependent damping is mainly caused by the nucleation and motion of dislocation; the damping of Mg increased exponentially with the temperature, and the damping peck appeared at 440 K is attributed to the appearance of dislocations at the grain boundaries which may be caused by boundaries self-diffusion. Graphic