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

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 (similar to 300 degrees C) and similar doses (similar to 2.0 dpa). The neutron-irradiated alloy contained visible interstitial dislocation loops with b = 111, and on average similar to 5 nm in size. The density varied from 2 +/- 1 x 10(20) m(-3) (in the matrix far from dislocations and boundaries) to 1.2 +/- 0.3 x10(23) m(-3) (close to helical dislocation lines). Chromium alpha'-phase precipitates were also identified at a density of 7.4 +/- 0.4 x10(23) m(-3). Self-ion irradiation produced mostly homogeneously distributed dislocation loops (6-7 nm on average), and with a greater fraction of 100 loops (similar to 40%) than was seen in the neutron-irradiated alloy, and at a density of 6.8 +/- 0.8 x10(22) 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 neutronirradiated sample. Chromium alpha'-phases were also identified in the proton-irradiated sample at a density of 2.5 +/- 0.3 x 10(23) m(-3), and large voids (up to 7 nm) were found at a density over 10(22)m(-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 x10(22) m(-3), while close to helical dislocation lines the density was 8.1 +/- 1.3 x10(22) m(-3). (c) 2020 Elsevier B.V. All rights reserved.