Effect of Al additions on grain refinement and mechanical properties of Mg-Sm alloys

The effect of Al additions on grain refinement and mechanical properties of Mg-Sm alloys has been investigated. The addition of 3 wt.% Al led to significant grain refinement of Mg-xSm (x = 4, 6 and 8 wt.%) alloys due to the formation of Al2Sm particles which acted as active nucleant particles for the Mg matrix. An orientation relationship (1¯11)Al2Sm//(0002)Mg,[1¯2¯1]Al2Sm//[112¯0]Mg,[01¯1]Al2Sm//[011¯0]Mg was reproducibly observed between α-Mg and Al2Sm. Furthermore, the Mg-4Sm alloy refined by Al additions had higher ultimate tensile strength and elongation than that refined by Zr which is considered as the most potent grain refiner for Mg alloys.