Microstructural evolution during liquid phase sintering: Part II. Microstructural coarsening

Abstract

During liquid phase sintering, microstructural coarsening takes place. One mechanism by which this occurs is Ostwald ripening. Alternatively, particle coalescence also leads to a concomitant reduction in the solid particle surface area per unit volume. In isolated structures in which particle-particle contacts are made, the rate of coarsening by coalescence is limited by the time between particle contacts, for this is long compared to the time to fuse two particles together. In skeletal structures the “coalescence time” limits coarsening by coalescence since this is long in comparison to the time between contacts. Expressions for the rate of particle coarsening are developed for the different mechanisms and different particle morphologies. The results of these calculations are combined with the microstructure maps developed in Part I of this paper to refine these maps so that they predict both the morphology developed and the dominant mechanism of coarsening in liquid phase sintered systems.