Molecular Dynamics Investigation On The Distribution Morphology Of Solute Atoms In Al-mg Alloy

The dislocation slip is the main way of the plastic deformation in metal materials; and the dislocation will be influenced during the movement, thus the plastic function of metal materials will be influenced. In the microcosmic, the Molecular Dynamics simulation method and the Embedded Atom method was used in this paper to simulate the interactions between single edge dislocation and substitutional solute atoms in Al-Mg alloy; through the research of different manifestations of the interactions between dislocation and solute atoms under different conditions, the connections between those manifestations and macroscopical plastic behaviors of the material were analyzed. The main conclusions are as following:(1) In normal temperature, the diffusion velocity of Mg atoms rises with the increment of the density of vacancies in Al cell. Under none strain condition and after the dislocation was introduced, the Cottrell atmosphere around the dislocation core was formed through the diffusion of the solute atoms; and the density of this atomic atmosphere increased with the increment of the distance to the dislocation line.(2) In normal temperature, there are 3 manifestations of the interactions between dislocation and solute atoms with different deformation velocities: the dislocation was pinned by solute atoms while the strain rate is in low level; the dislocation depinned while the strain rate is in high level; the pinning and depinning are ambiguity while the strain rate is in middle level, thereby the physical mechanism of the PLC effect in alloy is given by the simulation under microcosmic situation.(3) Under none strain condition, the trend that the solute atoms gather to the dislocation core become weaker with the increment of temperature; the density of the atomic atmosphere decreased with the increase of the temperature; the solute atoms distribute diffusely in high temperature.(4) T = 500K, there are also 3 manifestations of the interactions between dislocation and solute atoms with different deformation velocities; the pinning effect become weaker due to the density of atom atmosphere reduced compared with the case in normal temperature.