RELATION BETWEEN PERCOLATION AND PARTICLE COORDINATION IN BINARY POWDER MIXTURES

Deformation processing of composite materials is often affected by the percolation of inclusions, which may form a connective network supporting a significant part of the applied pressure and to hinder the densification of the matrix powder. By numerical simulation it was found that the critical volume fraction of inclusions required to form the first percolative cluster strongly depends on the inclusion to matrix particle size ratio. Moreover the fraction of inclusions belonging to a connective cluster is a size-ratio-insensitive function of the inclusion-inclusion coordination number. Using this correlation and an analytical model for particle coordination, a simple scheme is proposed to predict the percolation within bimodal powder mixtures. Interest of these results for understanding pressure transmission during processing of particulate composites is also discussed.