PSEUDO-STABLE STATES

The kinetics of the disorder --> B2 order transformation in a binary alloy was studied in the pair approximation and by Monte Carlo simulations. When a state is approached for which the free energy has a saddle point, the kinetic evolution of the alloy slows or even stalls. Because the state at the saddle point is an unstable state, its apparent stability is deceptive. This special state at the saddle point is an example of a 'pseudo-stable state'. It is shown that, a low temperatures, saddle points in the free-energy surface are expected. Close approaches to a saddle-point state are facilitated by a long time scale for the relaxation of long-range order.