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

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 degrees C. The particles coarsened and the structure recovered only slightly during annealing at 550 degrees 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 degrees 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. (c) 2007 Published by Elsevier B.V.