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

摘要

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℃. The particles coarsened and the structure recovered only slightly during annealing at 550℃ for 20min 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℃ 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.