A novel high-strength, high-ductility and high-corrosion-resistance FeAlMnC low-density alloy

The as-quenched Fe–8.68 wt.% Al–30.5 wt.% Mn–1.85 wt.% C alloy is plasma-nitrided at 500 °C for 8 h. The nitrided layer obtained is 40 μm thick and composed predominantly of AlN, with a small amount of Fe4N. The resultant surface hardness (1860 Hv), substrate hardness (550 Hv), ductility (33.6%) and corrosion resistance in 3.5% NaCl solution in the present nitrided alloy are far superior to those obtained previously in optimally nitrided high-strength alloy steels, as well as martensitic and precipitation-hardening stainless steels.