Ni has been widely reported as stabilise FCC phase in steels, similar to Mn and C ). However, the first report of B2-(Ni,Fe)Al phase stabilisation by addition of ~5wt.% Ni to Fe-16Mn-9Al-Ni (wt.%) TRIPLEX steels (with a microstructure comprising of FCC and κ phases) was first obtained from the work of . While Al accounts for low density (~5.5-6.5 g/cc), the room temperature microstructure of B2s Fe-Mn-Al-Ni-C steels typically comprises of B2 precipitates in FCC matrix. B2 phase is rich in Fe, Al and Ni . On the other hand, C and Mn have been reported to undergo preferential partitioning to FCC matrix . In addition to the above, a number of literatures also report the presence of (i) Ni and Al-rich BCC phase in FCC matrix ), (ii) B2-(Ni,Fe)Al precipitates in BCC phase , and (iii) L'12 structured κ-carbides in BCC phase and FCC matrix . However, there is still a limited understanding on the correlation between overall alloy composition and phase evolution in these steels.