Experiments were conducted to examine the grain refiningmechanisms in AM60B, pureMg, andMg–6%Al
with the addition of 5 wt% aluminum carbide (Al4C3). Grain refinement was observed in the AM60B and
pureMg with the addition of 5 wt% Al4C3 via two differentmechanisms respectively, i.e. duplex nucleation
hypothesis (Al4C3 →Al8Mn5 →-Mg) in AM60B and Al4C3 nuclei hypothesis (Al4C3 →-Mg) in pure Mg.
It is suggested that Mn is required to facilitate significant grain refinement in Mg–Al alloys containing
≥6% Al due to the segregating behavior of Al4C3 particles to the solid–liquid (S–L) interface. Mechanical
properties (yield strength, tensile strength, ductility, and microhardness) were enhanced by the addition
of Al4C3 to AM60B alloy.