In this study, a new austenitic Fe-28%Mn-9%Al-6%Cr-1.8%C (in mass%) alloy is developed. Because the alloy contains a high density of fine (Fe,Mn) 3 AlC carbides within the austenite matrix, the alloy in the as-quenched condition exhibits an excellent combination of strength and ductility comparable to that of the aged FeMnAlC alloys. In addition, owing to the formation of a layer of Cr and Al oxides in the passive film formed on the alloys, the corrosion potential E corr (À538 mV) and the pitting potential E pp (À25 mV) of the present alloy in 3.5% NaCl solution are considerably higher than the E corr (À920$À789 mV) and E pp (À500$À240 mV) values of the as-quenched and aged FeMnAlC alloys. Whereas the tensile strength of the present alloy is almost the same as that of conventional AISI 410 martensitic stainless steel, the present alloy possesses superior ductility than AISI 410 martensitic stainless steel. Furthermore, in 3.5% NaCl solution, the E pp (À25 mV) of the present alloy is noticeably higher than that (À250$À100 mV) of the conventional AISI 410 martensitic stainless steel. These results indicate that the present alloy in the as-quenched condition can possess high-strength and high-ductility as well as moderate corrosion resistance.

No abstract

As-quenched microstructure of the Fe-24.6 at% Al-7.5 at% Ti alloy was a mixture of (A2+L2 1 ) phases. When the as-quenched alloy was aged at 1173 K for moderate times, the L2 1 domains grew considerably and B2 phase was formed at a/2h100i anti-phase boundaries (APBs) as well as phase separation from well-grown L2 1 to (B2+L2 1 Ã ) occurred basically contiguous to the APBs, where L2 1 Ã is also a L2 1 -type phase. With continued aging at 1173 K, the phase separation would proceed toward the whole well-grown L2 1 domains. This microstructural evolution has not been reported in the Fe-Al-Ti alloy systems before.