SYMPOSIA PAPER Published: 01 January 1985

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


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.

Author Information

Brager, HR
Hanford Engineering Development Laboratory, Richland, WA
Garner, FA
Hanford Engineering Development Laboratory, Richland, WA
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Developed by Committee: E10
Pages: 139–150
DOI: 10.1520/STP37358S
ISBN-EB: 978-0-8031-4935-9
ISBN-13: 978-0-8031-0450-1