Transmutation-induced precipitation in tungsten irradiated with a mixed energy neutron spectrum

Journal Article · Wed Nov 21 00:00:00 EST 2018 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2018.11.032· OSTI ID:1484124

Hu, Xunxiang ^[1]; Parish, Chad M. ^[1]; Wang, Kun ^[1]; Koyanagi, Takaaki ^[1]; Eftink, Benjamin Paul ^[2]; Katoh, Yutai ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Transmutation-induced precipitation in neutron-irradiated tungsten is an important performance concern for its application as plasma facing material in fusion reactors. In this study, segregation and precipitation of transmutant elements in single crystal and polycrystal tungsten irradiated at 460–1100 °C to 0.02–2.4 displacements per atom (dpa) in the High Flux Isotope Reactor were investigated using transmission electron microscopy. The results indicated that nanoscale W-Re-Os clusters were identified in the low dose regime from 0.02 to 0.44 dpa with irradiation temperature lower than 800 °C while acicular-shape precipitates formed when irradiation dose is higher than 1.5 dpa. A tentative roadmap of the kinetics process of the transmutation-induced precipitation in neutron-irradiated tungsten is presented characterizing the defect features (i.e., W-Re-Os clusters and precipitates) consisting of transmutant elements in tungsten irradiated to various doses. All TEM-visible voids were associated with the acicular-shape precipitates. Voids were formed prior to the formation of acicular-shape precipitates and act as strong trapping sites for mobile species involved in the precipitation together with dislocations. Thermal stability of W-Re-Os clusters was assessed by performing a 2-h anneal at 1200 °C on tungsten irradiated to 0.44 dpa at 705 °C. In conclusion, the kinetics process of transmutant elements and radiation defects are discussed to reveal the underlying mechanisms controlling the formation of precipitates in tungsten.

• Research Organization: Los Alamos National Laboratory (LANL); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
• Grant/Contract Number: 89233218CNA000001; AC05-00OR22725; AC52-06NA25396
• OSTI ID: 1484124
• Alternate ID(s): OSTI ID: 1636988; OSTI ID: 1484661
• Report Number(s): LA-UR-18-28278
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: C Vol. 165; ISSN 1359-6454
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Neutron irradiation
Plasma facing material
Precipitation
Transmutation
Tungsten