Electric current effects in spark plasma sintering: From the evidence of physical phenomenon to constitutive equation formulation

TL;DR

This study investigates how different electric current densities during spark plasma sintering influence ZrN powders, revealing that higher currents improve deformability and reduce flow stress through enhanced dislocation motion.

Contribution

It provides experimental evidence linking electric current density to sintering behavior and develops a constitutive equation for ZrN under SPS conditions.

Findings

Higher electric current density increases deformability of ZrN.

Electric current flow enhances dislocation motion in ZrN.

Flow stress decreases with increased electric current density.

Abstract

The 3 heating modes are utilized to make ZrN powders have 3 different levels of the electric current density at the same temperature during spark plasma sintering (SPS). The constitutive equation of sintering for SPS is applied to the experimental porosity evolution of ZrN from three SPS modes, and this showed high electric current density increase the electric current assisted deformability value of ZrN pellets, resulting in a reduction of the flow stress. The electric current flow enhances the dislocation motion, which was experimentally proved and analyzed by modified Williamson-Hall equation applying to X-ray diffraction results, and the mechanical strength test of ZrN pellets.