Phase Field Crystal Simulation Of Edge Dislocation Motion Under Shear Strain

The phase field crystal method is a multi-scale numerical simulation method. PFC model can describe characteristics of nano-materials structure and properties in atomic scale, and reveal features of atom motion and the movement of defects at 10-12～10-6s time scale. It had been widely applied to simulate dislocation movement and dissociation, epitaxial growth, as well as the deformation and premelting of grain boundary, so the research has profound significance. So the main content of this paper is study the motion of edge dislocation glide and climb about the impact of strain rate and temperature parameter for two-dimensional hexagonal lattice bicrystal system under shear stress by the advanced crystal phase-field method. The main conclusions as follows:1. The free energy of standard PFC model is improved by introducing interaction term which is coupled applied shear force field with periodical atomic density function, and it can obtain the new free energy function that incorporated the effect of external shear strain.2. Exerting the different strain rate of external shear stress to the single-phase one-dislocation bicrystal system under the different temperature parameter, finding by the study, the edge dislocation jumpily glides along with burgers vector to the liquid area, which of velocity is faster and faster with the sostenuto exerting of applied stress strain. With increasing strain rate and the parameter of temperature, the glide of edge dislocation to the liquid is gradually accelerated. And when the direction of applied shear stress was changes, the glide direction of edge dislocation also changes and its specific direction depends on the direction of external strain.3. For the simulation of single-phase double-dislocation single-grain-boundary bicrystal system applied the different strain rate of external shear stress under the same temperature parameter, by detailedly calculating the free energy of the system and the position of edge dislocation at every moment, we finds that two edge dislocations only jumpily glides faster and faster along with burgers vector and the glide direction of two dislocations is same and its specific direction depend on the direction of external stress. What’s more the glide velocity is accelerates with the increasing of applied strain rate. However considering the single-phase double-dislocation double-grain-boundary bicrystal system applied external shear stress under the same temperature parameter, we can see the movement of two edge dislocations are jumpy glide along with burgers vector, and their glide direction are parallel and opposite. The same as above, the glide velocity is gradually accelerated with the increasing of applied strain rate and the glide direction depends on the direction of applied shear stress. In addition, when the distance of two dislocations is reduced, the velocity of two dislocations is gradually slow down. Conversely, when the distance of two dislocations is increased, the velocity of two dislocations is gradually accelerated.4. Applying the different strain rate of external shear stress to the two-phase one-dislocation bicrystal system under the same temperature parameter, the movement of dislocation is not only glide along with burgers vector but climb in the direction which is perpendicular with burgers vector. When applied stress strain rate is great, the movement of dislocation is jumpy glide, and its velocity is gradually accelerated at first and then keeps invariant. When applied stress strain rate is decreased, the movement of dislocation is not glide but that jumpy glide and jumpy climb are appearing at the same time. When applied stress strain rate is continue decreased, dislocation keeps stationary state in our simulation scope. Besides the glide velocity is gradually slow down with the decreasing of applied strain rate.5. The motion of edge dislocation in the two-phase one-dislocation bicrystal system is calculated using the methods of two-dimensional dislocation dynamics. Compared to the result in PFC model, it is found that the result by two-dimensional dislocation dynamics is consistent with by PFC. That is not only prove the validity of the method of PFC, also can reflect the advantage of PFC method that it well consider periodic atomic arrangement.In this paper, the movement of edge dislocation is reasonably simulated in different systems under shear strain, and it vividly reveals the process of dislocation movement and system’s evolution. Therefore, the study can provide valuable reference information for the actual material production and processed deformation.