Deformation assisted nucleation of continuous nanoprecipitates in Mg–Al alloys

Abstract

Conventional aging of magnesium alloys results in a low number density of laths providing poor precipitate strengthening. We demonstrate that deformation driven precipitation (DDP) of Mg-Al (6 and 9 wt.%) alloys produces a high density of nanoprecipitates with small aspect ratios within grain interiors. Nanoindentation of these samples yields much higher hardness values compared to conventionally peak aged samples. The precipitate number density correlates with the dislocation densities observed in experiments and calculated using a strain hardening model. We argue that dislocation multiplication increases the number of heterogeneous precipitate nucleation sites and thereby enhances precipitation.