Authors:
Silvia Baselli (University of Trento, Italy),
Alberto Molinari (University of Trento, Italy)
Abstract:
The thermodynamic driving force of sintering is the decrease of the Gibbs free energy related to the excess of specific surface area of the powder. Nevertheless, for cold compacted green parts, the mass transport mechanisms which allow atoms to move to form the neck are promoted by the deformation in compaction that acts as a mechanical driving force expressed through the geometrical and structural activity. The powder particles are in contact over a surface, condition that affects the geometrical relationships in the neck region. The material is strain hardened, the concentration of structural defects is higher than that in the starting powder (enhanced diffusivity). The effect on sintering shrinkage of the geometrical activity has been explained in previous works and a theoretical model is available. To highlight how structural activity acts, a dilatometry study has been carried out on ferrous materials (plain iron and AISI 316L) and different powder morphology.
DOI:
https://doi.org/10.59499/WP225372160