| With the microscopic phase-field model, the atomic-scale computer simulation programs of the binary model alloys including coherent strain energy during the precipitation were firstly worked out based on the microscopic elasticity theory and microscopic diffusion equation. It can be applied to the whole precipitation process and composition range. Any prior assumptions on the new phase structure or transformation path was unnecessary, the possible nonequilibrium phases and atomic clustering could be described automatically, the relevant information of time of the precipitation structures were obtained.The precipitation courses of the low composition alloys and the medial density alloys near the low density alloys could be delayed by the coherent strain energy. The heavier the coherent strain was, the smaller the fluctuations of the composition profiles were, and the narrower the protruding width of the composition profile curves were. With the increase of coherent strain energy, the precipitation mechanism of medial composition alloys near the high density alloys were becoming from the mixture processes which possed the characteristics of both non-classical nucleation growth and spinodal decomposition mechanisms to the processes which possed only the characteristics of non-classical nucleation growth. The coherent strain energy put off spinodal decomposition to a certain extent and made its precipitation mechanism change from typical spinodal decomposition mechanism to the mixture processes which possed the characteristics of both non-classical nucleation growth and spinodal decomposition mechanisms. With the elastic strain energy increased, the arrangement orientation increased, from spherical-shaped precipitates or flocculent structure distributed randomly with isotropic morphology to the anisotropic structure aligned along the elastically soft directions. Quasi-periodical macrolattice structures and sandwich shaped structures etc were formed. |
PDF Full Text Request