Three-dimensional Phase Field Crystal Simulation Of Three-dimensional Dislocation Premelting And Melting Under Stress

Scientists pay attention to grain boundary premelting because it can change macro properties of polycrystalline materials.It's difficult for us to observe these phenomenas because the general grain boundaries are only a few atomic layer thick,so we choose to use the computer simulation for the experimental deficiencies.In order to improve and develop the performance of materials,it is necessary to establish a numerical simulation method based on microscopic scale to predict the functional properties of materials and simulate premelting and melting phenomena of crystals.In this paper,three-dimensional phase field crystal method is used to study dislocation motion process and phenomena of stress acting in grain boundary,the main results are as follows:1?When the sample reaches a certain temperature,? B = 0.0250,the dislocation appears melting,and with the increase of temperature ? B,the area and radius becomes larger.Indicating that the system near melting temperature at grain boundary of the dislocation induced grain boundary to appear premelting.When it tends to be stable under stress,dislocations are close to each other and finally annihilation as a complete grain boundary.With the temperature ? B increasing,AB>0.0250,the area and radius becomes larger than before.Which can be obtained that system's temperature can determine the dislocation's melting,the higher temperature of system,the more prone to melting.However,the melting takes place not only at melting point but lower than melting point.When melting tends to be stable,dislocations close to each other,eventually connected.2.When the X-axis uniaxial stress is applied to sample,the dislocations are close to each other?attracted to each other and eventually connected,dislocation is gradually compressed by the X-axis into a flat circle;When the Y-axis uniaxial stress is applied to sample,the dislocation is gradually flattened by Y-axis into a flat circle,but the dislocations do not attract each other.However,the free energy curves of these two modes are the same,indicate the mechanism of motion is the same.3?After the shear stress is applied to the sample,the dislocation is slippery in X-axis direction and is climbing in Y-axis.The dislocations are still attracting each other.From the simulation results,it can be concluded that dislocations are closer to the center of the atomic layer,the dislocations become more,the melting areas and radius become smallers,the more intense melting occurs,and the dislocations finally connected.In this study,three-dimensional phase field crystal method is used to study dislocation motion process and phenomena of stress acting in grain boundary,consistent with the experiment,the study of the theory of the structure is obtained to change the macroscopic properties of polycrystalline materials has important guiding significance.