Modification of near-eutectic Al–Si alloys with rare earth element samarium

The modification of near-eutectic Al-Si alloy with samarium additions (0–0.9 wt.% content) has been studied. The thermal analysis results indicated that the addition of Sm in Al-12Si alloy caused a depression of eutectic temperature (ΔTE). And it was found that Sm was capable of breaking down the primary α-A1 phases, giving rise to an increment in the number of dendrites. Simultaneous primary Si refinement and eutectic modification were achieved by Sm addition. When 0.6 wt.% Sm was added to the alloy, the silicon in Al-12Si alloy was best refined and showed a fully modified, fine fibrous eutectic structure; the primary α-Al phase appears as a slightly dual dendritic-cellular nature and a pine-tree structure. Moreover, the mechanical properties were investigated by the tensile test. A good combination of ultimate tensile strength (217 MPa) and elongation (1.3%) was obtained when the addition of Sm was up to 0.6 wt.%.