Improving creep resistance of Al-12 wt.% Ce alloy by microalloying with Sc

Abstract The near-eutectic Al-12 wt.% Ce alloy has been alloyed with 0.4 wt.% Sc to improve its creep resistance. A bidirectional influence between Sc and Ce has been identified: (i) the Ce element suppresses the Sc partition between the liquid and solid phases during solidification, as implied by the reduction of Sc microsegregation in the as-cast ingot; (ii) the Sc atoms migrate towards the Al11Ce3 interface to form Al3Sc thin layer or particles upon aging. The former effect promotes the spatial uniformity of Al3Sc precipitate distribution in the Al matrix and the latter one introduces additional lattice misfit strain to the Al11Ce3/Al α phase boundary inhibiting matrix dislocations to climb over the Al11Ce3 lamellae. Both effects can improve the creep resistance of the aged Al-12Ce-0.4Sc alloy showing a high tensile stress threshold for dislocation creep of ∼ 60 MPa at 300  ∘ C.