Creep behavior of the die-cast Mg-Al alloy AS21

Creep behavior of the die-cast Mg-Al-based alloy AS21 was investigated at temperatures up to 150 °C in compression. The obtained stress exponent n is in the range of 13-19. Microstructure observation clarified that the die-cast magnesium alloy is hardened by the stable rod-shaped Mg2Si precipitates. The induction of a threshold stress into the analysis leads to a stress exponent of 5, which suggests that creep is controlled by the dislocation climb process. The origin of the threshold stress can be related to Orowan strengthening and an additional strengthening. The additional strength contribution may come from the dislocation loop debris stored at the Mg2Si rods.