Dislocation motion in plastic deformation of nano polycrystalline metal materials: a phase field crystal method study

The evolution mechanisms of grain boundaries and dislocations, including grain morphology, grain boundary structure, and dislocation motion during plastic deformation in polycrystalline composites at low and high temperatures, are simulated by phase field crystal method. The plastic deformation of nano polycrystalline composites includes four stages: the annihilation of adjacent dislocations on grain boundaries, the absorption of grain boundary dislocations, the emission of grain boundary fold dislocations, and the annihilation of dislocations in grains. With the increase of temperature, the motion of dislocation changes from slip to climb and slip. At high-temperature r = -0.25, the attraction of grain boundary to dislocation is greater than that between different dislocations. At low-temperature r = -0.40, different dislocations annihilate to form new dislocation pairs, which are absorbed by the grain boundaries. This research is helpful to understand the interaction mechanism between grain boundaries and dislocations in nano polycrystalline composites, and it is proposed that the mode and rate of dislocation entering grain boundary can be controlled by temperature, so as to regulate the mechanical properties of nano polycrystalline materials.

Automated summary

The evolution mechanisms of grain boundaries and dislocations in polycrystalline composites at low and high temperatures were studied using the phase field crystal method. The plastic deformation of nano polycrystalline composites involves four stages, and the motion of dislocation changes with temperature. The research shows that the mode and rate of dislocation entering grain boundary can be controlled by temperature, which can regulate the mechanical properties of nano polycrystalline materials.