Pc-Visualization of Phase Transitions in Alloys •••Kinetics of Ordering with Phase Separation
If an alloy, which was originally in the state of a uniform and disordered solid solution, is brought into a mixed phase field of the phase diagram, then the process of phase separation takes place either by nucleation and growth of precipitates or by spinodal decomposition. On the other hand when an alloy is aged in an ordered phase field, the process of ordering develops in the alloy, until ordered domains of opposite phases grow into an antiphase ordered domain structure. Furthermore, in some alloys, such as Fe-Al and Fe-Si, the process of ordering sometimes accompany a phase separation resulting in a two-phase state of order and disorder[1–3]. These processes are caused by migration of solute atoms to create a new phase of inhomogeniety, which is thermodynamically more stable than the original homogeneous phase, and are regarded as examples of relaxation from a nonequilibrium state to the one of thermal equilibrium.
KeywordsPhase Separation Phase Field Solute Atom Spinodal Decomposition Isothermal Aging
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