Microstructure, mechanical properties and corrosion behaviour of dilute Al–Sc–Zr alloy prepared by powder metallurgy

Abstract

Dilute Al–0.5 wt.% Sc–0.4 wt.% Zr alloy was prepared by powder metallurgy. Fine (sub)grain structure developed and fine coherent Al 3(Sc, Zr) particles precipitated during extrusion at 350 °C. The particles coarsened and the structure recovered only slightly during annealing at 550 °C for 20 min without a sign of recrystallization. Mechanical properties of the PM AlScZr alloy are comparable to those of Al alloy AA6061-T6 at room temperature and better at temperatures over 250 °C also than those of PM Al–6 wt.% Mg–Sc alloy with 1.1 and 1.9 wt.% Sc. Potentiodynamic polarisation experiments and intergranular corrosion test ascertained a greatly higher corrosion resistance of the PM AlScZr alloy compared with the commercial AA6061-T6 Al alloy.