Solid State Sintering of Two Component Systems with Solubility

Abstract

The driving force for “voluntary” (pressureless) sintering is the degradation of the free energy of the disperse body. For solid phase sintering of a one-component system, this is expressed in a reduction of external and internal surface and in the annihilation of lattice defects. In an heterogeneous system with components which are soluble into one another in addition, there are efforts to decrease the gradient of the chemical potential (homogenization) present in the contact range of chemically different particles. For that reason, during sintering of heterogeneous systems, a foreign diffusion caused by concentration gradients superimposes on the self-diffusion caused by capillary forces. That part of the sintering process where pore space is eliminated as well as chemical reactions take place between the initial components of the powder mixture (phase formations) is defined as reaction sintering.