Computer simulation of the mechanism of ordered precipitates of Al-Li alloy in external energy filed

A atomic-scale computer simulation programs of δ′(Al₃Li) based on the microscopic diffusion equation and non-equilibrium free energy were firstly worked out, which can be used to process the problem relating with time. The precipitation mechanism of δ′ was investigated by simulating the atomic pictures and calculating the order parameters, etc., and the variation in precipitation mechanism with the nearest interchange interaction energy (W₁), particularly the precipitation behavior of 13.5at%Li in Al-Li alloys were interpreted for the first time. It is found that the ordering reaction take place before the atom cluster processing. With the W₁ increase, the precipitation incubation period of δ′ is shortened, the range of ordered phase decrease, and the number of ordered phase increase. The ordering process and atom clustering is promoted and the formation of the disordered phase is blocked while the nearest interchange interaction energy increase with the increase of W₁, the time in which the ordering of the alloy is the most is moved up, and the ordering degree of the alloy is increased.