Monte Carlo Simulation Of The Interaction Between Dislocation And Solute Atoms In Plastic Deformation Of Alloys

The influence of the interaction between dislocation and solute atoms on the macroscopic mechanical behavior of the alloys is extraordinary great, and the interaction also influences the way by which alloys deform at the microscopic scale. With the development of automobile industry and urgent requirement of the automobile light weight, the research of the serrated yielding effect which influences the plastic formability of the Al alloys becomes very important. To study the interaction between dislocation and solute atoms may help to establish some theoretical foundation for the link between microscopic parameters and the macroscopic mechanical behavior of alloys. The dynamic Monte Carlo method was used in this paper to simulate the interaction between a single edge dislocation and substitutional solute atoms. The main contents are as follows:1. A dynamic Monte Carlo model was established to simulate two critical states (the dislocation is always static and the solute concentration is zero). When the dislocation is always static, the simulation results show that there is a Cottrell atmosphere around the dislocation core, and a diffuse solute atmosphere far from the core. The results also verify the feasibility of the simulation method.2. Supposing there is no interaction between solute atoms, the feature of dislocation motion and the distribution of solutes are obtained at different external stresses in the dynamic simulation. The results reflect that at small external stress the dislocation is efficiently pinned by solute atoms with low velocity; and at high external stress the dislocation motion is nearly unaffected by solute atoms and the velocity is high; whereas bifurcation of dislocation motion typified by velocity jumps has been found at intermediate stress.3. The influences of solute concentration and solute volume dilation on the dislocation velocity and the dislocation's critical de-pinning stress were simulated. The results reflect that the dislocation motion have two branches of high velocity and low velocity with the change of the solute concentration and the volume dilation; the dislocation critical de-pinning stress rises with the increment of the solute concentration and the volume dilation. 4. Considering the interaction between the solute atoms, we analyzed the influence of solute-solute interaction on the solute distribution in the static simulation, and the feature of dislocation motion in the dynamic simulation. The simulation results reflect the concurrence of the dislocation pinning and de-pinning, which exhibits the microscopic mechanism of the serrated yielding effect.