NONLINEAR RELAXATION DYNAMICS IN DECOMPOSING ALLOYS - ONE-DIMENSIONALCAHN-HILLIARD MODEL

The coarsening process in decomposing alloys is studied within the one -dimensional (1D) Cahn-Hilliard model using both the analytical and nu merical methods. We have developed the analytical approach based on th e solitonlike description of interacting phase boundaries and obtained the equations of their motion. For a single 1D nucleus in the infinit e medium the equation of the interface motion appears to be essentiall y nonlocal in time. The peculiarities of the dynamic behavior of this system are studied for an arbitrary initial nucleus size ao. For a(0)< a(c) similar to ln(1/h) the characteristic time scale of the nucleus d issolution is found as a function of a(0) and the supersaturation h in the system. In the limit a(0) much greater than a(c) we obtained the well-known square-root dependence of the nucleus size a similar to h r oot t. The late stage of the spinodal decomposition in multilayered st ructures has been investigated The specific features of the period dou bling process are studied.