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

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-alpha 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 similar to 60 MPa at 300 degrees C. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The introduction of 0.4 wt.% Sc into the near-eutectic Al-12 wt.% Ce alloy has shown bidirectional influence with Ce, leading to reduced Sc microsegregation and increased lattice misfit strain. These effects improve the creep resistance of the alloy by promoting spatial uniformity of Al3Sc precipitates and inhibiting matrix dislocation climb.