Light element analysis of irradiation-induced precipitates in Ti-modified 316 stainless steel
G and n phases are complex nickel silicides which commonly form in Fe-Ni-Cr based stainless steels and superalloys during neutron irradiation at 400-600°C. Both phases are cubic and are structurally similar to the common carbides M2 3C6 and M6C which form in many of the same alloys during thermal aging. Although G and n have been analyzed previously by energy-dispersive x-ray spectrometry (EDXS), little is known about their carbon contents.To further determine the compositional relationships between the G/n silicides and the M 23C 6/M6C carbides, an irradiated Ti-modified 316 stainless steel specimen containing 0.05 to 0.5μm particles of G and n was analyzed by means of electron energy loss spectroscopy (ELS) and EDXS in a field emission gun scanning transmission electron microscope (STEM). The alloy, LSI, has the nominal composition of Fe-16.8Cr-13.5Ni-l.9Mo-0.87Si-2.0Mn-.15Ti-.045C and was irradiated to 2 x 1022n/cm2, E >0.1 MeV, at 510°C in the EBR-II breeder test reactor.