Effect of neutron irradiation on deformation mechanisms operating during tensile testing of Zr–2.5Nb

Long, Fei; Balogh, Levente; Brown, Donald W.; Mosbrucker, Paula; Skippon, Travis; Judge, C. D.; Daymond, Mark R.

doi:10.1016/j.actamat.2015.09.032

Cited by 55 publications

(10 citation statements)

References 46 publications

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“…Details on the fabrication, metallurgy and application of the alloy have been given by Holt (2008); of relevance to this investigation, the final stages of processing include a cold-work step followed by a mild anneal, which results in cold-work dislocations still being present. This manuscript focuses on the characterization of the radiation defects present in the phase, the properties of which, owing to its high volume fraction, will dominate the response of the alloy during plastic deformation (Long et al, 2016). The irradiated samples were removed from PTs which were in service for seven years in a CANDU reactor at an operating temperature of $523 K and had experienced a fluence of 1.6 Â 10 24 m À2 of fast neutrons (E > 1 MeV).…”

Section: Comparison With Experimental Datamentioning

confidence: 99%

Contrast factors of irradiation-induced dislocation loops in hexagonal materials

2016

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Irradiation‐induced defects, such as dislocation loops, significantly affect the mechanical properties of structural alloys, altering slip and influencing creep and growth. As a consequence, the quantitative characterization of irradiation‐influenced defect structures as a function of dose, thermal treatments and/or cold work is essential for models which predict changes in mechanical properties due to the accumulation of irradiation defects. Whole pattern diffraction line profile analysis (DLPA) is a modern tool for microstructure characterization based on first‐principles physical models, well established for dislocation density measurements in plastically deformed materials. However, the DLPA procedures that have been tailored for deformed materials account for the strain anisotropy of hexagonal crystals with theoretical contrast factors calculated specifically for dislocation types generated by plasticity which, if directly applied to irradiated materials, will inherently introduce inaccuracies. In an effort to specifically address dislocation structures consisting of irradiation defects, a method was developed to calculate theoretical contrast factors for any general elliptically shaped dislocation loop. The values of the contrast factors are calculated and compiled in tables for six common elliptical ⟨a⟩‐type and ⟨c + a⟩‐type loops for ten hexagonal crystals, in order to provide a database for future DLPA work on irradiated materials. The use of the dislocation loop specific contrast factors is demonstrated on neutron‐irradiated Zr–2.5Nb.

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Section: Comparison With Experimental Datamentioning

confidence: 99%

Contrast factors of irradiation-induced dislocation loops in hexagonal materials

2016

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“…The critical resolved shear stress (CRSS) necessary to activate glide of c+a dislocations strongly depends on the temperature but is always much higher than the CRSS of a dislocation glide [7,17], thus explaining the strong plastic anisotropy of zirconium single crystals. An increased activity of c+a slip is observed in irradiated zirconium alloys, as the hardening induced by irradiation defects appears stronger on a slip systems than on c + a pyramidal slip [14,26], thus partly compensating for the friction difference between the two types of dislocations.…”

Section: Introductionmentioning

confidence: 98%

Mobility of 〈c+a〉 dislocations in zirconium

et al. 2020

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Plasticity in hexagonal close-packed zirconium is mainly controlled by the glide of dislocations with 1/3 1210 Burgers vectors. As these dislocations cannot accommodate deformation in the [0001] direction, twinning or glide of c + a dislocations, i.e. dislocations with 1/3 1213 Burgers vector, have to be activated. We have performed in situ straining experiments in a transmission electron microscope to study the glide of c + a dislocations in two different zirconium samples, pure zirconium and Zircaloy-4, at room temperature. These experiments show that c + a dislocations exclusively glide in first-order pyramidal planes with cross-slip being activated. A much stronger lattice friction is opposing the glide of c + a dislocations when their orientation corresponds to the a direction defined by the intersection of their glide plane with the basal plane. This results in long dislocations straightened along a which glide either viscously or jerkily. This a direction governs the motion of segments with other orientations, whose shape is merely driven by the minimization of the line tension. The friction due to solute atoms is also discussed.

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“…A physically-based crystal plasticity model was proposed to study the contact force and gap opening of fuel rod assembly by Patra and Tome [13]. The effects of fast neutron irradiation on the tensile deformation mechanism of Zr-2.5 pressure tube samples was studied by in situ neutron diffraction [14]. It was found that the starting stress of base plane <a> slip and cylinder <a> slip increased due to neutron diffraction, while the influence of cone < c + a > slip was small and became the dominant deformation mechanism.…”

Section: Introductionmentioning

confidence: 99%

Coupled Thermomechanical Responses of Zirconium Alloy System Claddings under Neutron Irradiation

et al. 2021

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Zirconium (Zr) alloy is a promising fuel cladding material used widely in nuclear reactors. Usually, it is in service for a long time under the effects of neutron radiation with high temperature and high pressure, which results in thermomechanical coupling behavior during the service process. Focusing on the UO2/Zr fuel elements, the macroscopic thermomechanical coupling responses of pure Zr, Zr-Sn, and Zr-Nb binary system alloys, as well as Zr-Sn-Nb ternary system alloy as cladding materials, were studied under neutron irradiation. As a heat source, the thermal conductivity and thermal expansion coefficient models of the UO2 core were established, and an irradiation growth model of a pure Zr and Zr alloy multisystem was built. Based on the user material subroutine (UMAT) with ABAQUS, the current theoretical model was implemented into the finite element framework, and the consequent thermomechanical coupling behavior under irradiation was calculated. The distribution of temperature, the stress field of the fuel cladding, and their evolution over time were analyzed. It was found that the stress and displacement of the cladding were sensitive to alloying elements due to irradiated growth.

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Effect of neutron irradiation on deformation mechanisms operating during tensile testing of Zr–2.5Nb

Cited by 55 publications

References 46 publications

Contrast factors of irradiation-induced dislocation loops in hexagonal materials

Contrast factors of irradiation-induced dislocation loops in hexagonal materials

Mobility of 〈c+a〉 dislocations in zirconium

Coupled Thermomechanical Responses of Zirconium Alloy System Claddings under Neutron Irradiation

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