On the influence of porosity on the portevin-le chatelier effect in sintered iron

Sintered irons of four different porosities were strained in tension at temperatures between 295 (room temperature) and 873 K. Serrated stress-strain curves and high work hardening in the temperature range from 333 to 693 K, for all porosities, were characteristic of dynamic strain aging. The activation energy for the onset of serration was ±0.82 eV and was independent of porosity. On the contrary, the parameter β from the relation for dislocation density increased with increasing porosity.