Evaluation of densification mechanisms of liquid-phase sintering

The contact flattening between grains has long been considered to be the de nsification mechanism during liquid-phase sintering. Recently, however, we proposed pore filling as being the major mechanism. In this investigation, we critically examine the two densification mechanisms by calculating their contributions to the sintering. The calculation shows that the contact fla ttening can be operative at the early stage for systems with a dihedral ang le of zero degrees. However, its contribution to grain shape change and com pact shrinkage is insignificant compared with that of the grain growth. A c onsideration of microstructures in real systems further suggests that the c ontribution of contact flattening is much less than the calculated value an d is negligible from the beginning of the liquid-phase sintering. In fact, pore filling, which is induced by grain growth, appears to be essentially t he only densification mechanism. An exemplified calculation of densificatio n kinetics by pore filling is also presented and its implication discussed.