Effects of transmutation elements on the microstructural evolution and electrical resistivity of neutron-irradiated tungsten

Tanno, Takashi; Hasegawa, Akira; He, Jian Chao; Fujiwara, M.; Satou, Mamoru; Nogami, Shuhei; Abe, Katsunori; Shishido, T.

doi:10.1016/j.jnucmat.2008.12.091

Cited by 94 publications

(71 citation statements)

References 7 publications

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“…The structure of these precipitates is consistent with σ (W 7 Re 6 ) and χ (WRe 3 ) intermetallic phases, which under equilibrium conditions only occur at temperatures and Re concentrations substantially higher than those found in neutron irradiation studies [12]. A principal signature of the formation of these intermetallic structures in body-centered cubic (bcc) W is the sharp increase in hardness and embrittlement [8][9][10]. Qualitatively similar observations have been recently made in W-2Re and W-1Re-1Os alloys subjected to heavy ion irradiation [13,14], clearly establishing a link between primary damage production and Re precipitation.…”

Section: Introductionsupporting

confidence: 69%

Mechanism of nucleation and incipient growth of Re clusters in irradiated W-Re alloys from kinetic Monte Carlo simulations

et al. 2017

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7High-temperature, high-dose, neutron irradiation of W results in the formation of Re-rich clusters at concentrations one order of magnitude lower than the thermodynamic solubility limit. These clusters may eventually transform into brittle W-Re intermetallic phases, which can lead to high levels of hardening and thermal conductivity losses. Standard theories of radiation enhanced diffusion and precipitation cannot explain the formation of these precipitates and so understanding the mechanism by which nonequilibrium clusters form under irradiation is crucial to predict materials degradation and devise mitigation strategies. Here we carry out a thermodynamic study of W-Re alloys and conduct kinetic Monte Carlo simulations of Re cluster formation in irradiated W2Re alloys using a generalized Hamiltonian for crystals containing point defects parameterized entirely with electronic structure calculations. Our model incorporates recently-gained mechanistic information of mixedinterstitial solute transport, which is seen to control cluster nucleation and growth by forming quasi-spherical nuclei after an average incubation time of 13.5(±8.5) s at 1800 K. These nuclei are seen to grow by attracting more mixed interstitials bringing solute atoms, which in turns attracts vacancies leading to recombination and solute agglomeration. Owing to the arrival of both Re and W atoms from the mixed dumbbells, the clusters are not fully dense in Re, which amounts to no more than 50% of the atomic concentration of the cluster near the center. Our simulations are in qualitative agreement with recent atom probe examinations of ion irradiated W-2Re systems at 773 K.

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Section: Introductionsupporting

confidence: 69%

Mechanism of nucleation and incipient growth of Re clusters in irradiated W-Re alloys from kinetic Monte Carlo simulations

et al. 2017

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“…From the viewpoint of the transmutation effect of W under the fusion reactor operation, the samples irradiated in HFIR may receive overestimated transmutation effects (i.e., composition change, amounts of precipitates and solute-transmuted atoms, and strength and ductility changes) relative to those in fast reactors and fusion reactors. In our previous studies, neutron irradiation experiments using the experimental fast reactor Joyo operated by JAEA were carried out [17,18], and no precipitates were observed in pure W after neutron irradiation with almost the same conditions because of the lower thermal neutron flux. For precise investigation of the neutron irradiation effect of W under neutron irradiation conditions in fusion reactors using the HFIR, control of the neutron flux using a thermal neutron shield is necessary.…”

Section: Resultsmentioning

confidence: 99%

Microstructural development of tungsten and tungsten–rhenium alloys due to neutron irradiation in HFIR

Fukuda

Yabuuchi

Nogami

et al. 2014

Journal of Nuclear Materials

132

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“…Transmutation products also influence the nature of atomic displacement damage accumulation during neutron irradiation. Experiments performed in the JOYO reactor found that accumulation of vacancies results in the formation of a void lattice [9][10][11], however, this phenomenon was not observed in HFIR irradiations [7,12,13]. It was inferred that due to the higher thermal neutron content of the HFIR neutron spectrum, solid transmutation products were generated at a high enough rate to suppress void lattice formation.…”

Section: Introductionmentioning

confidence: 99%

Ab initio study of interstitial cluster interaction with Re, Os, and Ta in W

Setyawan

Nandipati

Kurtz

2017

Journal of Nuclear Materials

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The stability of tungsten self-interstitial atom (SIA) clusters is studied using first-principles methods. Clusters from one to seven SIAs are systematically explored from 1264 unique configurations. Finite-size effect of the simulation cell is corrected based on the scaling of formation energy versus inverse volume cell. Furthermore, the accuracy of the calculations is improved by treating the 5p semicore states as valence states. Configurations of the three most stable clusters in each cluster size n are presented, which consist of parallel [111] dumbbells. The evolution of these clusters leading to small dislocation loops is discussed. The binding energy of size-n clusters is analyzed relative to an n → (n-1) + 1 dissociation and is shown to increase with size. Extrapolation for n > 7 is presented using a dislocation loop model. In addition, the interaction of these clusters with a substitutional Re, Os, or Ta solute is explored by replacing one of the dumbbells with the solute. Rhenium and Os strongly attract these clusters, but Ta strongly repels. The strongest interaction is found when the solute is located on the periphery of the cluster rather than in the middle. The magnitude of this interaction decreases with cluster size. Empirical fits to describe the trend of the solute binding energy are presented.

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Effects of transmutation elements on the microstructural evolution and electrical resistivity of neutron-irradiated tungsten

Cited by 94 publications

References 7 publications

Mechanism of nucleation and incipient growth of Re clusters in irradiated W-Re alloys from kinetic Monte Carlo simulations

Mechanism of nucleation and incipient growth of Re clusters in irradiated W-Re alloys from kinetic Monte Carlo simulations

Microstructural development of tungsten and tungsten–rhenium alloys due to neutron irradiation in HFIR

Ab initio study of interstitial cluster interaction with Re, Os, and Ta in W

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