Coarsening of Second-Phase Precipitates
Document Type
Book
Publication Date
1-1-2023
Abstract
In Chap. 1 we established that a system is unstable thermodynamically until its free energy has reached a minimum. On the other hand, a particle of the second phase has substantial amount of excess free energy associated with its interfacial area, a conclusion which we reached in the Gibbsian theory of capillarity; see Sect. 4.2.1. Therefore, the two-phase system consisting of precipitate particles of various sizes embedded into a sea of parent phase (matrix) is not stable. Hence, the decrease of the total area of the particles may serve as a driving force of the process of stabilization of the system. It is advantageous for smaller particles to dissolve and to transfer their mass to the larger ones since smaller particles contribute, on a per volume basis, more to the interfacial energy of the system than do larger particles. Such a process was termed Ostwald ripening or coarsening after the physical chemist Ostwald who originally described the process qualitatively [1]. Since the excess energy associated with the total surface area is usually small, coarsening typically manifest itself as the last stage of a first-order phase transformation process, at the end of which the system will have reached its lowest energy state of a single particle in the matrix.
Recommended Citation
Umantsev, Alexander, "Coarsening of Second-Phase Precipitates" (2023). College of Health, Science, and Technology. 300.
https://digitalcommons.uncfsu.edu/college_health_science_technology/300