PHASE-SEPARATION BY DIRECTIONAL QUENCHING AND MORPHOLOGICAL TRANSITION

With the help of a two-dimensional numerical stimulation the time evolution of the phase separation of a mixture is studied for various types of quenching. Firstly, the usual homogeneous types of quenching is briefly reviewed. Secondly, the spatiotemporal inhomogeneous type of quenching is studied. By setting the quench boundary, which is the boundary between the stable phase and the unstable phase, and shifting it with a constant velocity, the time evolution of the domain morphologies are examined numerically. Three different types of domain morphologies are found. One is irregular and is essentially equivalent to that produced by the homogeneous quench. The other two are regular and are characteristic of the inhomogeneous quenching process. One of the regular domain morphologies is parallel to the quench boundary on the average, whereas the other regular one is perpendicular to the quench boundary. The transition between the two regular morphologies is sharp.