Field Of The Precipitation Process Of Al-li Alloy Under The Atomic Level Computer Simulations

The influence of outer potential field on single atom and atomic interaction energy on precipitation mechanism of ' (Al3Li) phase in Al-Li alloys were investigated by computer simulation.Based on Thomas-Fermi equation and analysis in the influence of electric field on inner potential field, boundary condition of inner potential field of Thomas-Fermi equation influenced by electric field was established for the first time. And it was concluded that with elevation of intensity of electric field, the influence of positive electric field on energy of atom is increased; the influence of negative electric field on energy of atom is decreased firstly, then increased.Based on the microscopic diffusion equation and nonequilibrium free energy function, the atomic-scale computer simulation programs of Al3Li(8'phase) were worked out in order to study the influence of atomic interaction energy on precipitation mechanism of ' phase. Atomic images, order parameters, volume fraction of ordered phase and density of particulate were simulated and calculated.It is firstly found that for alloys in metastable region, with enhancement of atomic interaction energy, volume fraction and density of ' phase particulate are increased, size and nucle'ation rate of ordered phase raised, decline pace of composition in disordered matrix around the order phase is accelerated, composition order parameter and long range order parameter of ordered phase increased, i.e. process of clustering and ordering are accelerated.It is found for the first time that for alloys in instable region, with enhancement of atomic interaction energy, pregnant period of ' phase is shortened, degree of ordering and composition order parameter of ordered phase is increased, process of clustering in ordered phase accelerated, i.e. process of congruent ordering is quickened and velocity of spinodal decomposition is expedited.It is firstly found that for alloys in transitional region, with enhancement of atomic interaction energy, pregnant period of ' phase is shortened dramatically, and process of clustering accelerated remarkably, stages of growth and coarseningof ' phase brought forward, i.e. precipitation mechanism of alloy in transitional region incline to that of alloy in instable region.