Phase Field Crystal Simulation Of Dislocation Movement Under The Stress

The phase field crystal method is a multi-scale numerical simulation method developing in recent years, which describes the lattice arrangement of atoms in the crystal by average atomic density field variables. Because this method contains many properties of the periodic structure, such as crystal orientation, elastoplastic deformation and so on, can reflect physical properties natural. It had been widely applied to simulate dislocation movement, nanoscale twins formed, abrikosov vortex lattices in superconductors, as well as magnetic thin films, research significance profoundly. Plastic flow in periodic systems is typically mediated by the motion of line defects or dislocations, in developing the meaningful theory of plasticity, the biggest challenge is how to link the microscopic behavior of individual dislocation to micro system performance. Now days we can’t obtain the observation of edge dislocation migration process fully in real experiments, microscopic simulation study about this part is also not a lot. So the main contents of this paper is using phase field crystal method spaning the large of range scale, studying on diffusive time scales within the frame work of a continuum field theory, simulating edge dislocations’s dynamic subjected to shear and compressive strain, It is shown that the natural features of these processes and without to consider the theory of elasticity or microscopic Peiers potentials. In this work we discussed strain rate, supercooling, atomic radius impact on the process of dislocation glide and climb, From the perspective of speed and free energy analyzed edge dislocation motion mechanism, The main conclusions as follows.1. Bringing to bear on the hexagonal phase which contain single edge dislocation, whatever glide and climb of the dislocation in the early stage of the evolution, the speed is slow, the edge dislocation keep uniform motion state in the middle and later periods. The speed of edge dislocation glide decreased with the increasing of degree supercooling of system. The speed of glide and average shear strain are increasing with the strain rate. The speed of climb is increasing with the degree supercooling of system and the compressive stress rate. 2. Multiple edge dislocation’s reaction under the action of internal stress of system, evolution result tend to make lattice structure rules and complete, because this is a stably state; in this process edge dislocation’s vector keep conservative.3. Due to the driving force of evolution is the variation of energy, free energy towards the direction of the minimum under the control of dynamic equation. The greater atomic radius the faster speed of motion. Dislocation movement can release distortion energy effectively, significantly reduced system energy.Research results of this study can recreates the edge dislocation evolution under the effect of external stress reasonable. Under the temperature and strain rate which the real experiment can close, study can provides reference information for the actual material design and machined.