Helical dislocations: Observation of vacancy defect bias of screw dislocations in neutron irradiated Fe–9Cr

Haley, Jack C.; Liu, Fengxian; Tarleton, Edmund; Cocks, A.C.F.; Odette, G.R.; Lozano-Pérez, Sergio; Roberts, SG

doi:10.1016/j.actamat.2019.09.031

Cited by 37 publications

(21 citation statements)

References 73 publications

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“…In Figure 8, a selection of dislocation loops from a high density region of the proton-irradiated Fe9Cr is shown, which inside-outside contrast suggests are interstitial-type. This is as expected based on previous work [65][66][67], and agrees well with the findings of interstitial loops in the neutron irradiated Fe9Cr alloy [47]. Figure 9 shows the same analysis for the self-ion irradiated Fe9Cr; we also show here details of the tilt series used to identify the sense of the habit plane of the indicated loops.…”

Section: -The Nature Of Dislocation Loopssupporting

confidence: 91%

“…This resulted in the ferritic grain structure shown in Figure 1(a) with a low dislocation density of ~6×10 12 /m 2 , as shown in Figure 1(b). The same alloy was also studied by Bachhav et al [37], Bhattacharyya et al [46], and Haley et al [47], and also the same alloy heat prior to the annealing treatment by Gelles et al [48]. In atomic-percent, the composition of the alloy is 9.36% Cr, 0.05% Ni, 0.02% V, and 0.01% each of C, Si, P and Mn (see APT study by Bachhav et al [37]).…”

Section: -Materialsmentioning

confidence: 81%

“…To remove 30kV Ga+ FIB damage, a final thinning from ~180nm foil thickness to ~100nm was conducted using 2kV Ga+ ions. Precession weak-beam dark field was used to image the dislocation loops, following the technique described by Haley et al [47], using a JEOL 2100 microscope operating at 200kV with a LaB6 source and scripted beam control. Dislocation loop and void measurements were conducted using the standard techniques described by Jenkins and Kirk [58].…”

Section: -Tem Analysis Methodsmentioning

confidence: 99%

“…The amount of transmutation gas was predicted to be low (~0.4 He-appm and 7.3 H-appm). Analysis of the microstructure of this neutron-irradiated alloy has already been conducted for a separate paper [47].…”

Section: -Irradiation Experimentsmentioning

confidence: 99%

“…The interstitial or vacancy nature of the dislocation loops was measured by the inside-outside method [59]. The results of this analysis on the neutron-irradiated material is shown in reference [47]. In Figure 8, a selection of dislocation loops from a high density region of the proton-irradiated Fe9Cr is shown, which inside-outside contrast suggests are interstitial-type.…”

Section: -The Nature Of Dislocation Loopsmentioning

confidence: 99%

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

Haley

Shubeita

Wady

et al. 2020

Journal of Nuclear Materials

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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, 2MeV Fe+ ions or 1.2MeV 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 ~5nm in size. The density varied from 2±1x10 20 m -3 (in the matrix far from dislocations and boundaries) to 1.2±0.3x10 23 m -3 (close to helical dislocation lines). Chromium α'-phase precipitates were also identified at a density of 7.4±0.4x10 23 m -3 . Self-ion irradiation produced mostly homogeneously distributed dislocation loops (6-7nm 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 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 neutron-irradiated sample. Chromium α'-phases were also identified in the proton-irradiated sample at a density of 2.5±0.3x10 23 m -3 , and large voids (up to 7nm) 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 .

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