Radiation-enhanced diffusion in amorphous Pd-Cu-Si

Dyrbye, K.; Bo, Jiang; ttiger,; Pampus, K.; Torp, B.

doi:10.1103/physrevb.38.8562

Cited by 11 publications

(5 citation statements)

References 6 publications

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“…However, there is limited understanding in the possible mechanisms for RED in SiC GBs. For highly disordered GBs, that can be considered approximately amorphous (high-angle GBs), the literature on RED in amorphous materials [71][72][73][74][75] strongly suggests that radiation can change diffusional behaviors. These previously proposed mechanisms includes the collective diffusion via displacement chains [74], enhancement in radiation-induced destabilized regions [71][72][73], and enhancement by increase of free volume from irradiation [75].…”

Section: Discussionmentioning

confidence: 99%

“…For highly disordered GBs, that can be considered approximately amorphous (high-angle GBs), the literature on RED in amorphous materials [71][72][73][74][75] strongly suggests that radiation can change diffusional behaviors. These previously proposed mechanisms includes the collective diffusion via displacement chains [74], enhancement in radiation-induced destabilized regions [71][72][73], and enhancement by increase of free volume from irradiation [75]. Although there are still many uncertainties about these mechanisms, it is suggested that a RED of Ag through a percolating network of amorphous-like HEGBs may explain the observed radiation effects on Ag diffusion in SiC.…”

Section: Discussionmentioning

confidence: 99%

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Ag diffusion in SiC high-energy grain boundaries: Kinetic Monte Carlo study with first-principle calculations

Deng

Szlufarska

et al. 2016

Computational Materials Science

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The diffusion of silver (Ag) impurities in high energy grain boundaries (HEGBs) of cubic (3C) silicon carbide (SiC) is studied using an ab initio based kinetic Monte Carlo (kMC) model. This study assesses the hypothesis that the HEGB diffusion is responsible for Ag release in TristructuralIsotropic (TRISO) fuel particles, and provides a specific example to increase understanding of impurity diffusion in highly disordered grain boundaries. The HEGB environment was modeled by an amorphous SiC (a-SiC), which approximately represents the local environments of HEGBs. The structure and stability of Ag defects were calculated using ab initio methods based on Density Functional Theory (DFT). The defect energetics suggested that the fastest diffusion takes place via an interstitial mechanism in a-SiC and that is what is modeled. Interstitial sites were identified by a gridded search and transition states were computed using the climbing image nudged elastic band method. The formation energy of Ag interstitials (relative to bulk Ag) and the Kinetic Resolved Activation (EKRA) energies between them were well approximated with Gaussian distributions that were then sampled in the kMC. The diffusion of Ag was simulated with the effective medium model using kMC. Ag diffusion coefficients were estimated for the temperature range of 1200-1600°C. Ag in a HEGB is predicted to exhibit an Arrhenius type diffusion and with a diffusion prefactor and effective activation energy of (2.73 ± 1.09) × 10 −10 m 2 s −1 and 2.79 ± 0.18 eV, respectively. The comparison between HEGB results to other theoretical studies suggested not only that GB diffusion is predominant over bulk diffusion, but also that the HEGB is one of fastest grain boundary paths for Ag diffusion in SiC. The Ag diffusion coefficient in the HEGB shows a good agreement with ionimplantation measurements, but is 2-3 orders of magnitude lower than the reported diffusion coefficient values extracted from integral release measurements on in-and out-of-pile samples. The discrepancy between GB diffusion and integral release measurements suggests that other contributions are responsible for fast release of Ag in some experiments and we propose that these contributions may arise from radiation enhanced diffusion.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Ag diffusion in SiC high-energy grain boundaries: Kinetic Monte Carlo study with first-principle calculations

Deng

Szlufarska

et al. 2016

Computational Materials Science

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“…For highly disordered GBs that can be considered approximately amorphous (high-angle GBs), the literature on RED in amorphous materials strongly suggests that RED is likely. Diffusivities of impurities in various disordered (amorphous) materials can be enhanced by orders of magnitude due to irradiation [67][68][69][70][71][72][73]. Specifically, irradiation may increase the pre-factor [67][68][69] or decrease the activation energy [70][71][72][73] of the impurity diffusivity, depending on the diffusion mechanism.…”

Section: Discussion On Mechanisms Of Radiation Enhanced Diffusionmentioning

confidence: 99%

“…Diffusivities of impurities in various disordered (amorphous) materials can be enhanced by orders of magnitude due to irradiation [67][68][69][70][71][72][73]. Specifically, irradiation may increase the pre-factor [67][68][69] or decrease the activation energy [70][71][72][73] of the impurity diffusivity, depending on the diffusion mechanism. Mechanisms proposed for amorphous RED include changes in mediating point defect concentrations [72], irradiation impacting collective diffusion [74], and coupling to free volume [73].…”

Section: Discussion On Mechanisms Of Radiation Enhanced Diffusionmentioning

confidence: 99%

Effect of carbon ion irradiation on Ag diffusion in SiC

Leng

Gerczak

et al. 2016

Journal of Nuclear Materials

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Transport of Ag fission product through the silicon-carbide (SiC) diffusion barrier layer in TRISO fuel particles is of considerable interest given the application of this fuel type in high temperature gas-cooled reactor (HTGR) and other future reactor concepts. The reactor experiments indicate that radiation may play an important role in release of Ag; however so far the isolated effect of radiation on Ag diffusion has not been investigated in controlled laboratory experiments. In this study, we investigate the diffusion couples of Ag and polycrystalline 3C-SiC, as well as Ag and single crystalline 4H-SiC samples before and after irradiation with C 2+ ions. The diffusion couple samples were exposed to temperatures of 1500C, 1535C, and 1569C, and the ensuing diffusion profiles were analyzed by secondary ion mass spectrometry (SIMS). Diffusion coefficients calculated from these measurements indicate that Ag diffusion was greatly enhanced by carbon irradiation due to a combined effect of radiation damage on diffusion and the presence of grain boundaries in polycrystalline SiC samples.

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“…Early in 1972 Chen et al 3 found that the addition of Cu can significantly improve the thermal stability of Pd-Si MGs. As a result, the Pd 78 Cu 6 Si 16 MG, which lies close to the eutectic point of the ternary system has attracted interest due to a combination of excellent GFA, outstanding mechanical properties and promising hydrogen sensing ability 4 5 6 7 8 9 .…”

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confidence: 99%

Local structure order in Pd78Cu6Si16 liquid

Yue

Zhang

Sun

et al. 2015

Sci Rep

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The short-range order (SRO) in Pd78Cu6Si16 liquid was studied by high energy x-ray diffraction and ab initio molecular dynamics (MD) simulations. The calculated pair correlation functions at different temperatures agree well with the experimental results. The partial pair correlation functions from ab intio MD simulations indicate that Si atoms prefer to be uniformly distributed while Cu atoms tend to aggregate. By performing structure analysis using Honeycutt-Andersen index, Voronoi tessellation, and atomic cluster alignment method, we show that the icosahedron and face-centered cubic SRO increase upon cooling. The dominant SRO is the Pd-centered Pd9Si2 motif, namely the structure of which motif is similar to the structure of Pd-centered clusters in the Pd9Si2 crystal. The study further confirms the existence of trigonal prism capped with three half-octahedra that is reported as a structural unit in Pd-based amorphous alloys. The majority of Cu-centered clusters are icosahedra, suggesting that the presence of Cu is benefit to promote the glass forming ability.

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Radiation-enhanced diffusion in amorphous Pd-Cu-Si

Cited by 11 publications

References 6 publications

Ag diffusion in SiC high-energy grain boundaries: Kinetic Monte Carlo study with first-principle calculations

Ag diffusion in SiC high-energy grain boundaries: Kinetic Monte Carlo study with first-principle calculations

Effect of carbon ion irradiation on Ag diffusion in SiC

Local structure order in Pd78Cu6Si16 liquid

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