A Kinetic Theory of Nucleation in Multicomponent Systems

Nucleation governs the formation of new phases and extended defects in materials and plays a fundamental role in microstructural evolution under both thermal and irradiation conditions. Although Classical Nucleation Theory has long provided the foundation for describing these processes, its conventional formulations often become inadequate when applied to real materials with faceted interfaces, multicomponent compositions, elastic stresses, or irradiation-induced non-equilibrium conditions. This book presents a systematic development of a kinetic theory of nucleation that resolves several long-standing inconsistencies of conventional models by introducing a self-consistent treatment of mass transport, interface kinetics, and defect processes. A central result is the demonstration that nucleation kinetics is fundamentally controlled by the growth mechanism of supercritical clusters. In particular, systems with atomically smooth interfaces, where growth proceeds by Two-Dimensional Nucleation, exhibit nucleation behaviour that differs qualitatively from predictions of traditional models. The theory is developed for unary and binary systems and subsequently extended to multicomponent materials. Applications include precipitation in alloys, nucleation of coherent and incoherent particles, formation of voids and gas bubbles, dislocation loop nucleation, and radiation-induced defect evolution. Special attention is given to the role of Point Defects and Ballistic Re-Solution in controlling phase stability and nucleation kinetics under irradiation. Bridging fundamental theory, experimental interpretation, and predictive materials modelling, this book offers a unified framework for understanding nucleation phenomena in advanced structural and nuclear materials. The book is intended for researchers and advanced graduate students in theoretical physics and materials science. It will be of particular interest to specialists working on nucleation theory, phase transformations, defect formation and microstructural evolution in materials. It is especially relevant for researchers studying multicomponent alloys and irradiation effects in solids, as well as for those involved in modelling and interpretation of experimental data on phase precipitation and defect evolution.