Microstructural examination of neutron, proton and self-ion irradiation damage in a model Fe9Cr alloy

Journal article

Transmission electron microscopy (TEM) was used to compare the microstructural defects produced in an Fe9Cr model alloy during exposure to neutrons, protons, or self-ions. Samples from the same model alloy were irradiated using fission-neutrons, 2 MeV Fe + ions or 1.2 MeV protons at similar temperatures (∼300 °C) and similar doses (∼2.0dpa). The neutron-irradiated alloy contained visible interstitial dislocation loops with b = 111, and on average ∼5 nm in size. The density varied from 2±1 × 10²⁰ m^-3 (in the matrix far from dislocations and boundaries) to 1.2 ± 0.3 × 10²³ m^-3 (close to helical dislocation lines). Chromium α′-phase precipitates were also identified at a density of 7.4 ± 0.4 × 10²³ m^-3. Self-ion irradiation produced mostly homogeneously distributed dislocation loops (6–7 nm on average), and with a greater fraction of 100 loops (∼40%) than was seen in the neutron-irradiated alloy, and at a density of 6.8 ± 0.8 x10²² m^-3. In contrast to the loops produced by neutron irradiation, the self-ion irradiated Fe9Cr contained only vacancy-type loops. Chromium also remained in solution. Proton-irradiated Fe9Cr contained interstitial dislocation loops close to helical-dislocation segments, similar to the neutron-irradiated sample. Chromium α′-phases were also identified in the proton-irradiated sample at a density of 2.5 ± 0.3 × 10²³ m^-3, and large voids (up to 7 nm) were found at a density over 10²²m⁻³. Like the neutron-irradiated sample, the density of dislocation loops was also heterogeneously distributed; far from grain boundaries and dislocation lines the density was 2.5 ± 0.4 x10²² m^-3, while close to helical dislocation lines the density was 8.1 ± 1.3 x10²² m^-3.

Authors: Haley, JC; Lozano-Perez, S; de Moraes Shubeita, S; Wady, P; London, AJ

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Journal of Nuclear Materials
• Volume: 533
• Article number: 152130
• Publication date: 2020-03-29
• Acceptance date: 2020-03-22
• DOI: 10.1016/j.jnucmat.2020.152130
• ISSN: 0022-3115
• Language: English
• Keywords: FFR