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Microstructure evolution during creep testing at 750°C and 100MPa of Fe–20Cr–30Ni–2Nb (at.%) alloys with and without 0.4 Si, 0.2 Zr or 5.0 Al additions has been studied, in order to explore the viability of Fe-rich austenitic stainless alloys strengthened by intermetallic phases. Fine Fe₂Nb Laves phase dispersions with the size of less than 1μm within the γ-Fe matrix were obtained in the base and Si-modified alloys after aging at 800°C. The addition of Si helped to refine and stabilize the size of particles, resulting in finer and denser Fe₂Nb dispersion than that in the base alloy. The alloys with only solution heat-treatment exhibited superior creep resistance to the aged ones, which is due to dynamic precipitation of the Fe₂Nb Laves phase during creep testing with a size of 300–400nm, resulting in more effective pinning of dislocations. The base alloy also showed the meta-stable γ″-Ni₃Nb phase with a size of 50nm …