The kinetics of ordering in fcc alloys during the growth of a (001) monolayer is investigated by the kineticmean-field method. The evolution of the structure parameters is calculated. There is a transient ordered stateduring the growth process and its occurrence depends on the ratio of the atomic exchange rate to the evaporationrate. The growth process displays two stages of evolution. The first stage is the formation of a metastableordered state whose lifetime increases exponentially with the decrease of the temperature. The second stage is the evolution from the metastable ordered state to the equilibrium ordered state. The stoichiometric concentrationsof the metastable ordered state is found to be different from the equilibrium one. The influence of thetwo characteristic times related to the adsorption and the atomic migration on the kinetics of the growth isanalyzed.

We have investigated the kinetics of ordering and disordering in the ternary bcc Fe-Co-Al alloy using the micromaster equation method in the site approximation. We predict that there are various types of transient ordered states in the ternary bcc Fe-Co-Al alloy during the ordering from a quenched disordered state to the equilibrium ordered state. Two different mechanisms are accounted for the occurrence of the transient states. In the kinetics of disordering, the evolution of the order parameters shows fluctuations due to the difference in the diffusion coefficients.

The kinetics of ordering in the bcc ternary alloy is investigated by means of the micromasterequation method in the pair approximation. The time evolution of the long-range order andshort-range order parameters are calculated. A transient ordered state results in distinct features, such as stepwise variation, overshooting effects, and peaks in the evolution to different equilibriumphases. It is found that the development of short-range order in the ordering stage of the transientordered state is different from that in the equilibrium phase. Short-range order relaxes gradually inthe ordering stage of the transient ordered state in contrast to the fast change of short-range order in the ordering stage of the equilibrium phase.

The kinetics of ordering and disordering in the ternary b.c.c. Fe-Al-Ti alloy is investigated bymeans of the micro-master equation method. It was found that there are transient ordered states in theternary b.c.c. Fe-Al-Ti alloy during the ordering from a quenched disordered state to the equilibriumordered state. Two different mechanisms account for the occurrence of the transient states. In the kineticsof disordering, the evolution of the order parameters shows flctuations.

We have investigated the kinetics of a ternary system using the cluster variation method and the pathprobability method in the pair approximation. From the calculated metastable phase diagram and kineticpath of the system, we demonstrated the existence of transient ordered states during the relaxation fromthe completely disordered state to the equilibrium disordered state due to the difference of relaxationtime for the three species of atoms in ternary alloy. This suggests that it is possible to obtain anordered state in a quenching process of ternary alloy in the disordered phase region of equilibrium phasediagram.