Strengthening mechanisms of MgSi alloys

The origins of high room temperature strength of rapidly solidified (RS) Mg-high Si alloys have been analysed using various strengthening mechanism models. The analysis revealed that the high strength was attributed to the fine-grain strengthening mechanism as well as the strengthening mechanisms due to Mg2Si particles. A large contribution of the fine-grain strengthening mechanism results from the strong dependence of strength on grain size for h.c.p. metals. However, the strength of the RS alloys containing small particles (⩽1 μm) rapidly decreased at 473 K. This is explained by the critical particle size concept.