Densification mechanisms of spark plasma sintering: multi-step pressure dilatometry

The effects of electrical current and mechanical pressure on the densification of spherical copper powder during spark plasma sintering (SPS) are examined. A novel multi-step pressure dilatometry method is introduced to compare the constitutive behavior of the copper powder under nearly equivalent current-insulated and current-assisted SPS process conditions. The strain rate sensitivity agrees with that predicted for a dislocation climb-controlled creep densification mechanism for both processing setups. Accelerated densification rate leading to a higher final relative density is observed for the current-assisted SPS.