Effect of liquid phase on densification in electric-discharge compaction

The effect of liquid phase on densification in electric-discharge compaction (EDC) was explored in the present work. The temperature at contact area of particles in EDC was estimated from random packing model incorporated with electric current distributions. Consolidation of cemented carbide and tungsten heavy alloys was conducted under varying current densities. WC-11Co/Fe/WC-11Co sandwich powder compacts were designed to investigate the effect of liquid phase flow. It is found that the densification occurred only when liquid phase formed, and relative density increased with the increasing of liquid phase volume. In the case of WC-11Co powders, the faceted grain evolution occurred but the significant grain growth was hardly observed, which meant the densification was mainly induced by particle rearrangement. The depth of liquid penetration of Fe in WC-11Co/Fe/WC-11Co sandwich compact also agreed with that caused by particle rearrangement processing. The possible effects of electric current on densification were also discussed.