EFFECT OF ADDITIONAL MINOR ELEMENTS ON MICROSTRUCTURAL EVOLUTION OF NEUTRON-IRRADIATED FE-CR-MN ALLOYS

To study irradiation damage and the effects of additional elements on phase stability and void swelling, Fe-10Cr-15Mn and Fe-10Cr-15Mn-3Al alloys were neutron irradiated in FFTF/MOTA at 365, 420, 520 and 600-degrees-C to 1 X 10(22)/cm2, 9.54 X 10(22)/cm2, 9.56 X 10(22)/CM2, and 9.6 X 10(22)/cm2, respectively. The structures of these alloys were observed by TEM and the compositional changes were analyzed using a 200 kV TEM with an EDX analyzer. The alloys contained austenite and ferrite phases. The fraction of ferrite in the alloy with Al was larger than for in the pure Fe-10Cr-15Mn alloy. Voids were formed at each irradiation temperatures in the austenite phase but not in the ferrite. In the F-10Cr-15Mn alloy the phase transformation from austenite to alpha martensite phases occurred at 365 to 420-degrees-C and at higher temperature the ferrite phase was newly nucleated from austenite matrix. Furthermore a chi phase with higher Manganese was formed in the transformed alpha martensite but the occurrence of these new phases were not detected in the alloy with aluminum.