Microstructural evolution of CANDU spacer material Inconel X-750 under in situ ion irradiation

Zhang, He Ken; Yao, Zhongwen; Judge, C. D.; Griffiths, M.

doi:10.1016/j.jnucmat.2013.06.034

Cited by 52 publications

(13 citation statements)

References 35 publications

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“…This also results in the growth of a limited number of clusters, and hence a lower DY and a larger loop size. The similar trends of DY vs. temperature and loop size vs. temperature were also recently found in other materials regardless of their different crystal structures, such as in bcc pure Fe [28][29][30][31] and pure W [32][33][34], and in fcc pure Ni [35] and Ni alloys [36].…”

Section: Prismatic Loop Formationsupporting

confidence: 82%

Irradiation Induced Defect Clustering in Zircaloy-2

Yao

Daymond

et al. 2017

Applied Sciences

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Featured Application: The data and results will be helpful to evaluate the radiation damages in fuel cladding or calandria tube of nuclear power plants.Abstract: The effect of irradiation temperature and alloying elements on defect clustering behaviour directly from the cascade collapse in Zircaloy-2 is examined. The in-situ ioWn irradiation technique was employed to study the formation of -type dislocation loops by Kr ion irradiation at 573 K and 773 K, while the dependence of dislocation loop formationon the presence of alloying elements was investigated by comparing with the defect microstructures of pure Zr irradiated under similar conditions. The experimentally observed temperature dependence of defect clustering was further investigated using molecular dynamics (MD) simulations near the experimental irradiation temperatures. We particularly concentrate on yield and morphology of small defect clusters formed directly from cascade collapse at very low ion doses. Smaller loop size and higher defect yield (DY) in Zircaloy-2 as compared to pure Zr suggests that the presence of the major alloying element Sn increases the number of nucleation sites for the defect clusters but suppresses the point defect recombination. MD simulations at 600 and 800 K revealed that the production of both vacancy and interstitial clusters drops significantly with an increase of irradiation temperature, which is reflected in experimentally collected DY data.

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Section: Prismatic Loop Formationsupporting

confidence: 82%

Irradiation Induced Defect Clustering in Zircaloy-2

Yao

Daymond

et al. 2017

Applied Sciences

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“…In the single Ni ion-irradiated sample (Ni at 400°C), no cavities were detected (Figure 9), which is consistent with previous results on microstructural observation of X-750 after single ion irradiation without He pre-implantation. [9] It is worth mentioning that the cavity size measurements have been performed for each stopping peak location separately and the size distribution curve was plotted using the sum of all of that data. In case of He-Ni at 400°C, the cavity size was about the same diameter at all seven locations.…”

Section: Cavity Developmentmentioning

confidence: 99%

“…An alternative hardening model was proposed by Friedel-Kroupa-Hirsch (FKH) (Eq. [9]) and describes material hardening due to the presence of circular dislocation loops of Burgers vector magnitude b, diameter d, and number density N. [42] Dr ¼ 1 8 MlbdN…”

Section: Modeling Of Irradiation-induced Hardeningmentioning

confidence: 99%

“…[5,7,8] Furthermore, some studies have tried to emulate the effect of neutron irradiation on the microstructure of X-750 alloy by means of employing heavy ion irradiation under controlled irradiation conditions. [9][10][11] The results show that irradiation may affect the microstructure in different ways depending on irradiation temperature, irradiation dose, and dose rate. X-750 is an age-hardened Ni-based superalloy strengthened by precipitation of the c¢-Ni 3 (Ti, Al) phase with an L1 2 -ordered structure.…”

Section: Introductionmentioning

confidence: 95%

“…Our previous study on microstructural evolution in the X-750 alloy during dual-beam (He/Ni) irradiation clearly reveals that implanted helium atoms increase the stability of the c¢-phase with the result that disordering occurs at much higher irradiation doses compared to single heavy ion irradiation. [9,20] Furthermore, the size and density of interstitial-type defects such as the Frank loops increase with helium implantation, which is attributed to the hindering of vacancies and interstitial recombination by means of the consumption of irradiation-induced vacancies during cavity production and growth, with the consequent increase in the survival probabilities of free interstitials. [21] Therefore, helium may have a significant impact on post-irradiation mechanical properties by not only promoting cavity generation, but also by changing the precipitate stability and distribution of defects.…”

Section: Introductionmentioning

confidence: 99%

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Nano-scale Mechanical Properties and Microstructure of Irradiated X-750 Ni-Based Superalloy

Changizian

Brooks

Yao

et al. 2017

Metall Mater Trans A

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This study investigates the effect of irradiation on the mechanical properties of a Ni-based superalloy, X-750. 40 MeV Ni + ions were used to irradiate the X-750 up to 1 dpa with and without 5000 appm helium pre-implantation at room temperature and 400°C. Nano-indentation hardness tests were carried out at room temperature in the depth range of 200 to 1400 nm before and after irradiation. Cross-sectional TEM observations were performed on the irradiated materials to correlate the mechanical results with the microstructural evolution. The results show that helium pre-implantation enhances the irradiation-induced hardening due to generating a high density of small cavities and promoting the formation of larger Frank loops. In addition, nano-scale mechanical tests reveal that changing the subsequent Ni ion irradiation temperature from room temperature to 400°C, leads to changing of the mechanical response from a softening behavior to an irradiation-induced hardening. The c¢ precipitates became disordered after irradiation at room temperature, whereas the c¢-phase remained ordered during irradiation at 400°C. The softening effect of the c¢ instability outweighed the hardening impact of irradiation-induced defects such as cavities and Frank loops, leading to a hardness reduction for the room-temperature-irradiated material. Three different obstacle-hardening models were employed to assess the individual impact of each type of defect on the material's overall strength enhancement. Furthermore, the superposition principle was used for each model to estimate the overall irradiation-induced strengthening, which is compared to the results from the nano-hardness measurements.

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