Role of Al modification on the microstructure and mechanical properties of as-cast Mg-6Ce alloys

The effect of Al additions on grain refinement and mechanical properties of Mg-6Ce alloys has been investigated. Greatly grain coarsening were obtained when Al content are 1% and 2%, mainly due to both the weakening of the segregation effect of Ce solute and the lack of the effective nucleation sites. However, an addition of 3∼5% Al into the Mg-6Ce melt promotes the in situ formation of Al2Ce particles and reduce the grain size. Furthermore, active Al2Ce particles were observed at the centers of many refined grains. Crystallographic calculations confirmed that Al2Ce particles were effective grain refiners for α-Mg. The finest grains were achieved at 5% Al addition level, which corresponds to the size of 7∼10 μm with the highest number density of the active particles. The reasons of improvement of both the strength and ductility of the Mg-6Ce alloy containing Al were fine grain size and secondary phase strengthening.