Effects of substituting rare-earth elements for scandium in a precipitation-strengthened Al-0.08 at. %Sc alloy

The microhardness of Al-0.06 Sc-0.02 RE alloys (at.%, with RE (rare-earth) = Dy, Er, Gd, Sm, Y, or Yb) is measured as a function of aging time at 300 degrees C. As compared to Al-0.08 Sc, the ternary alloys exhibit: (i) the same incubation time, except for Al-0.06 Sc-0.02 Yb which hardens much faster; (ii) the same or reduced peak microhardnesses (which are higher than for Al-0.06 Sc); and (iii) the same over-aging behavior. All REs segregate to the core of Al-3(Sc1-xREx) precipitates. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.