Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling

Hofmann, Felix; Nguyen-Manh, D.; Gilbert, Mark R.; Beck, Christian E.; Eliason, Jeffrey K.; Maznev, A. A.; Liu, W.; Armstrong, David E.J.; Nelson, Keith A.; Dudarev, S. L.

doi:10.1016/j.actamat.2015.01.055

Cited by 137 publications

(157 citation statements)

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“…The availability of such data is still relatively limited as the majority of density functional calcul ations of defects performed so far focused on the accurate evaluation of energies of defects [42][43][44][45], rather than on the evaluation of elastic properties of defects [7,8,27,29,46]. The relaxation volume of a Frenkel pair can be approximated by the sum of relaxation volumes of an SIA and a vacancy.…”

Section: Relaxation Volumes Of Point Defects In Bcc Transition Metalsmentioning

confidence: 99%

“…For example, the elastic relaxation volume of a self-interstitial atom defect in tungsten, predicted by density functional theory, is Ω rel = 1.67Ω 0 , where Ω 0 is the volume of an atom, whereas the relaxation volume of a vacancy is Ω rel = −0.37Ω 0 , see e.g. [7,8]. The large positive mismatch between elastic relaxation volumes of self-interstitial and vacancy type defects in metals, which accumulate in the microstructure as a result of irradiation, gives rise to the local volumetric expansion, and produces stresses in materials exposed to irradiation, resulting in macroscopic swelling and heterogeneous deformation of reactor components.…”

Section: Introductionmentioning

confidence: 99%

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A multi-scale model for stresses, strains and swelling of reactor components under irradiation

et al. 2018

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Predicting strains, stresses and swelling in nuclear power plant components exposed to irradiation directly from the observed or computed defect and dislocation microstructure is a fundamental problem of fusion power plant design that has so far eluded a practical solution. We develop a model, free from parameters not accessible to direct evaluation or observation, that is able to provide estimates for irradiation-induced stresses and strains on a macroscopic scale, using information about the distribution of radiation defects produced by high-energy neutrons in the microstructure of materials. The model exploits the fact that elasticity equations involve no characteristic spatial scale, and hence admit a mathematical treatment that is an extension to that developed for the evaluation of elastic fields of defects on the nanoscale. In the analysis given below we use, as input, the radiation defect structure data derived from ab initio density functional calculations and large-scale molecular dynamics simulations of high-energy collision cascades. We show that strains, stresses and swelling can be evaluated using either integral equations, where the source function is given by the density of relaxation volumes of defects, or they can be computed from heterogeneous partial differential equations for the components of the stress tensor, where the density of body forces is proportional to the gradient of the density of relaxation volumes of defects. We perform a case study where strains and stresses are evaluated analytically and exactly, and develop a general finite element method implementation of the method, applicable to a broad range of predictive simulations of strains and stresses induced by irradiation in materials and components of any geometry in fission or fusion nuclear power plants.

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Section: Relaxation Volumes Of Point Defects In Bcc Transition Metalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A multi-scale model for stresses, strains and swelling of reactor components under irradiation

et al. 2018

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“…9 Recently, TGS has been shown to be a useful tool in evaluating the effects of irradiation in metallic systems. [10][11][12] In this technique, a spatially periodic material excitation is generated by periodic thermal excitation, itself produced by the interference pattern of two crossed pumping laser beams at the material surface. In reflective materials, this excitation manifests itself as surface displacement and/or transient reflectivity change.…”

mentioning

confidence: 99%

Time-resolved, dual heterodyne phase collection transient grating spectroscopy

Dennett

Short

2017

Applied Physics Letters

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The application of optical heterodyne detection for transient grating spectroscopy (TGS) using a fixed, binary phase mask often relies on taking the difference between signals captured at multiple heterodyne phases. To date, this has been accomplished by manually controlling the heterodyne phase between measurements with an optical flat. In this letter, an optical configuration is presented which allows for collection of TGS measurements at two heterodyne phases concurrently through the use of two independently phase controlled interrogation paths. This arrangement allows for complete, heterodyne amplified TGS measurements to be made in a manner not constrained by a mechanical actuation time. Measurements are instead constrained only by the desired signal-to-noise ratio. A temporal resolution of between 1 and 10 s, demonstrated here on single crystal metallic samples, will allow TGS experiments to be used as an in-situ, time-resolved monitoring technique for many material processing applications.

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“…One promising tool for these direct, mesoscale measurements is transient grating (TG) spectroscopy [13,14]. This technique optically induces and monitors monochromatic surface acoustic waves (SAWs) with micron-scale wavelengths over an area on the order of 0.01 mm 2 .…”

Section: Published By the American Physical Society Under The Terms Omentioning

confidence: 99%

Bridging the gap to mesoscale radiation materials science with transient grating spectroscopy

et al. 2016

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Direct mesoscale measurements of radiation-induced changes in the mechanical properties of bulk materials remain difficult to perform. Most widely used characterization techniques are either macro-or microscale in nature, focusing on overall properties or overly small areas for analysis. Linking the atomic structure of irradiated materials directly with their radiation-affected properties remains one of the largest unmet challenges in radiation materials science. By measuring the change in surface acoustic wave speed as a function of relative orientation on metallic single crystals, we demonstrate that transient grating (TG) spectroscopy experiments have the sensitivity necessary to detect radiation-induced material property changes. We also show that classical molecular dynamics (MD) simulations can be used to accurately simulate orientation-based changes in surface acoustic wave speed in TG experiments, by comparing with experimental measurements and theoretical predictions. The agreement between theory, simulation, and experiment gives confidence in classical MD as a predictive tool to simulate defect-based changes in elastic properties, which cannot yet be fully treated by theory. This ability is of critical importance for the informed use of TG spectroscopy to measure material property changes induced by radiation damage, which may vary by amounts formerly too small for reliable in situ detection. Finally, our MD simulation framework is used to study the effect of an imposed vacancy population on the acoustic response of several materials. The results of these studies indicate that TG experiments are well suited to the ex situ and in situ study of radiation-induced material property changes.

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Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling

Cited by 137 publications

References 70 publications

A multi-scale model for stresses, strains and swelling of reactor components under irradiation

A multi-scale model for stresses, strains and swelling of reactor components under irradiation

Time-resolved, dual heterodyne phase collection transient grating spectroscopy

Bridging the gap to mesoscale radiation materials science with transient grating spectroscopy

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