Feasibility study of 'elephant foot' phenomenon during liquid phase sintering of systems with volatile components

Based on investigations reported by many researchers, deformation of the specimen under its own weight at the bottom can be much higher than at the top. This effect is known as 'elephant foot' phenomenon due to the apparent shape of the samples after sintering. But it seems that the type of alloy is of relevance, and especially the alloys with volatile components have different behaviour. Samples of Cu-28Zn, with a volatile element (i.e. zinc) were compacted at 400 MPa and sintered in the range of 890-970 degrees C for 20 min. Although liquid phase settles to the bottom of the samples by gravitational force, this phenomenon did not appear in brass alloys. The change in chemical composition and consequently the microstructural gradient from surface to centre as a result of zinc evaporation results in a layer at and near the surface with high solid volume fraction. This layer prevents elephant foot formation.