2017 Volume 64 Issue 9 Pages 479-485
MgO particles dispersed AZ61B composite alloys were fabricated via equal channel angular bulk mechanical alloying (ECABMA) and following sintering and hot extrusion processes. α-Mg grain refinement was drastically occurred with increase in the MgO additive content of the composites due to dynamic recrystallization during hot extrusion. Regarding the micro hardness of the matrix, it increased with increase in MgO contents because of the synergy of the grain refinement and MgO hard particles dispersion strengthening effects. However, such a strengthening behavior was gradually decreased in the elevated temperature at 473 K. When comparing the strengthening effect by the grain refinement and MgO particles dispersion by using Hall-Petch coefficient at ambient and elevated temperatures, it was clarified that the latter effect was more dominant in the MgO/AZ61B composite alloys.
