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 °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 Al3(Sc1−xREx) precipitates.