Effect of Zr and Sc on Intermetallic Morphology and Hardening of an Al–Fe Alloy

Abstract

We studied the effect of zirconium and scandium on an Al-7 wt% Fe cast alloy with potential heat- and wear-resistant applications. An addition of 0.2% Zr resulted in thinning of primary Al3Fe particles, while an addition of 0.15% Zr and 0.15% Sc changed the morphology of primary intermetallics from needles to flower-like shape. While the addition of Zr did not affect the properties, the Zr + Sc joint additions increased the hardness of the as-cast Al–Fe alloy. The hardness of the base alloy increased upon annealing from 40 to 80 HV (450 °C, 2 h) and to 110 HV (350 °C, 20 h). The wear resistance of the Al–Fe alloy was also improved by Zr and Sc addition, especially after annealing. The observed effects are likely to be linked to the supersaturation of Zr and Sc in the aluminum solid solution during solidification and precipitation of dispersoids during annealing.