The External Potential Field Of Alloys The Role Of Computer Simulation Of Discrete And Continuous Method

In this paper, the computer simulation programs based on the continuum non-classical nucleation theory were firstly worked out, through which the order parameter, the radius of the ordered phase, the interface thickness and the critical nucleation energy were calculated. The comparison between the continuum theory and the discrete lattice dynamic model was carried out. The influences of the atomic interaction energy ( W1 and W2) to the precipitation mechanism of the Al-Li alloys in both metastable and intermediate regions were studied national and abroad for the first time. The results from the two methods are consistent.It was found that as the atomic interaction energy increased, the critical energy of the 8' ordered phase decreased and the nucleation rate increased for the alloys in both metastable and intermediate regions. It was found from the discrete lattice dynamic model: as the atomic interaction energy increased, the sizes and volume fractions of the ordered phase raised, decline speed of composition in disordered matrix around the ordered phase was accelerated, the processes of clustering and ordering were accelerated, and the grow speed of the stoichiometric ordered phase was quicken. It was found for the first time that the increase of the atomic interaction energy made the precipitation mechanism of alloys in metastable region inclined to that of alloys with higher composition. The influence degree of W1 was the least and that of both W1 and W2 was the most. At the early stage of precipitation, the interface thickness of alloy in the metastable region was nearly unchanged, which was nearly 0.7nm; but that of alloys in the transient region decreased from 0.8nm to 0.6nm, and the decrease speeds become slower with time.