ABSTRACT
Phase separation is ubiquitous, occurring in a diverse range of liquid-liquid mixtures, (metallic alloys, network glasses, polymer-polymer mixtures, rodlike molecule mixtures, surfactant solutions) regardless of the geometry and structure of the molecular constituents. Strategies that involve phase separation are often used to control the microstructural features and hence the properties of engineering materials. Phase diagrams are of particular utility since they identify the equilibrium structure (microstructural features, etc.) of a mixture at given temperature and composition ranges. The evolutionary, or transient, changes of the structure of a mixture due to changes in temperature that move it from one region of the phase diagram to another can be fascinating. One of the seminal papers on this topic describes the spinodal structure of a phase separated borosilicate network glass melt (Cahn 1969). The bicontinuous spinodal structures and, more importantly, signatures of spinodal decomposition (time dependencies of various characteristics of the structure) have been investigated in a wide range of systems in recent years, employing expe-rimental techniques such as microscopy (scanning and electron microscopy and scanning force microscopy) to examine cross-sections of samples (direct images) and scattering measurements (neutrons, X-rays, etc.) of the structure factor to learn about the spatial and temporal structure of the system. From a technological perspective, an understanding of this phenomenon is important. Spinodal decomposition processes influence the morphology of a wide range of alloys (metallic, polymeric, inorganic) and therefore determines a range of physical (mechanical, magnetic) and chemical (corrosion) properties. This phenomenon is often exploited to effectively tailor material microstructure.
