Anisotropic shrinkage induced by particle rearrangement in sintering

A microscopic model is presented which describes the anisotropic shrinkage induced by particle rearrangement during sintering. Two types of topological transitions in the rearrangement, that is the formation of a new contact, are illustrated in three-dimensional simulation of sintering of four spheres arranged in a rhombus. The shrinkage rate is shown to become anisotropic as the particle coordination number changes with rearrangement. A micromechanical principle is discussed with the use of sintering force and effective viscosity. The anisotropic shrinkage is caused by the additional sintering force acting on the new grain boundary formed at the rearrangement.