Morphological Evolution Diffusional Creep, and Sintering

MORPHOLOGICAL EVOLUTION DUE TO CAPILLARY AND APPLIED FORCES DIFFUSIONAL CREEP AND SINTERING 

Capillary forces induce morphological evolution of an interface toward uniform diffusion potential—which is also a condition for constant mean curvature for isotropic free surfaces (Chapter 14). If a microstructure has many internal interfaces, such as one with fine precipitates or a fine grain size, capillary forces drive mass between or across interfaces and cause coarsening (Chapter 15). Capillary-driven processes can occur simultaneously in systems containing both free surfaces and internal interfaces, such as a porous polycrystal. 

Applied forces can also induce mass flow between interfaces. When tensile forces are applied, atoms from an unloaded free surface will tend to diffuse toward internal interfaces that are normal to the loading direction this redistribution of mass causes the system to expand in the tensile direction. Applied compressive forces can superpose with capillary forces to cause shrinkage. In this chapter, we introduce a framework to treat the combined effects of capillary and applied mechanical forces on mass redistribution between surfaces and internal interfaces. 

Kinetics of Materials. By Robert W. Balluffi, Samuel M. Allen, and W. Craig Carter. 387 Copyright 2005 John Wiley Sons, Inc. 

Microstructures are generally too complex for exact models. In a polycrystalline microstructure, grain-boundary tractions will be distributed with respect to an applied load. Microstructures of porous bodies include isolated pores as well as pores attached to grain boundaries and triple junctions. Nevertheless, there are several simple representative geometries that illustrate general coupled phenomena and serve as good models for subsets of more complex structures. 

---

CHAPTER 16 MORPHOLOGICAL EVOLUTION DIFFUSIONAL CREEP. AND SINTERING... 

---