Enhanced densification of zinc powders through thermal cycling

The densification of zinc powders by uniaxial hot pressing is investigated under both isothermal and thermal cycling conditions. Thermal cycling results in enhanced densification kinetics as compared to isothermal compaction at the upper cycle temperature. Using mechanistic models of initial-stage powder densification, the experimental data are analyzed to reveal the creep stress-exponent and activation energy of the dominant densification mechanism. Consequently, the observed densification enhancement during thermal cycling is confirmed to be due to internal stress plasticity, which is produced by internal mismatch stresses between adjacent zinc grains with anisotropic thermal expansion.