SEDL / STP / STP870-EB / STP37358S



Microsegregation Observed in Fe-35.5Ni-7.5Cr Irradiated in EBR-II

Brager, HR
Senior research engineer and fellow scientist, Hanford Engineering Development Laboratory, Richland, WA

Garner, FA
Senior research engineer and fellow scientist, Hanford Engineering Development Laboratory, Richland, WA


Pages: 12    Published: Jan 1985


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Abstract

In another recent study of the compositional dependence of swelling in annealed iron-nickel-chromium alloys, it was found that some annealed alloys densified during irradiation. No precipitate phases were observed to form, however. At 593°C, one alloy, Fe-35.5Ni-7.5Cr, which was particularly resistant to swelling, increased in density 0.9% at 7.6 × 1022 neutrons (n)/cm2 (E > 0.1 MeV).

Examination by energy dispersive X-ray analysis revealed that substantial oscillations occur in the nickel content of the alloy, varying from 25 to 53% about the nominal level of 35.5%. These oscillations exhibit a period of ∼200 nm. Regions enriched in nickel are depleted in chromium and iron, and the reverse is true in regions of low nickel content. This spinodal-like process produces a net densification and also appears to eventually destroy the swelling resistance of the alloy. Once voids form in the nickel-poor chromium-rich regions, further segregation of nickel to void surfaces is expected to accelerate the loss of swelling resistance.


Keywords:
radiation, austenitic alloys, neutron irradiation, compositional modulation, densification, order-disorder, spinodal, swelling

Paper ID: STP37358S
Committee/Subcommittee: E10.08
DOI: 10.1520/STP37358S
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