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Sergiy V. Divinski - One of the best experts on this subject based on the ideXlab platform.
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Grain Boundary Diffusion of 59Fe in high-purity copper
Acta Materialia, 2019Co-Authors: Jens Ribbe, Vladimir A. Esin, Sergiy V. DivinskiAbstract:Grain Boundary Diffusion of iron in high purity polycrystalline copper is measured using the radiotracer technique and applying the 59Fe isotope. At lower temperatures, K, the measurements are performed under Harrison's C-type kinetic regime and the Grain Boundary Diffusion coefficient of Fe in Cu. Unconventional penetration profiles are measured for Fe Grain Boundary Diffusion in Cu at higher temperatures ( 949 K) under the intended B-type kinetic regime, in fact formal C-type profiles are systematically observed instead. Molecular dynamics simulation with the literature Finnis-Sinclair type interatomic potentials [Ackland et al., Phil. Mag. A, 1997] discovered an unexpected response of Cu Grain boundaries on a partial Fe coverage at temperatures above 900 K. A model of Fe penetration in polycrystalline Cu in such conditions is proposed, which explains the untypical shape of the penetration profiles. The combination of the B- and C-type Grain Boundary Diffusion measurements predict a strong segregation of Fe in Cu with a low segregation enthalpy.
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Grain Boundary Diffusion of 59Fe in high-purity copper
Acta Materialia, 2019Co-Authors: Jens Ribbe, Vladimir A. Esin, Sergiy V. DivinskiAbstract:Abstract Grain Boundary Diffusion of iron in high purity polycrystalline copper is measured using the radiotracer technique and applying the 59Fe isotope. At lower temperatures, T 949 K, the measurements are performed under Harrison's C-type kinetic regime and the Grain Boundary Diffusion coefficient of Fe in Cu, D gb , is determined, D gb = 5.6 ⋅ 10 − 6 × exp ( − 121 kJmol − 1 / R T ) m2/s. Unconventional penetration profiles are measured for Fe Grain Boundary Diffusion in Cu at higher temperatures ( ≥ 949 K) under the intended B-type kinetic regime, in fact formal C-type profiles are systematically observed instead. Molecular dynamics simulation with the literature Finnis-Sinclair type interatomic potentials [Ackland et al., Phil. Mag. A, 1997] discovered an unexpected response of Cu Grain boundaries on a partial Fe coverage at temperatures above 900 K. A model of Fe penetration in polycrystalline Cu in such conditions is proposed, which explains the untypical shape of the penetration profiles. The combination of the B- and C-type Grain Boundary Diffusion measurements predict a strong segregation of Fe in Cu with a low segregation enthalpy.
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Grain Boundary Diffusion and precipitates in B2 Ti 50.2 at.% Ni alloy
Intermetallics, 2015Co-Authors: Dan Dan Liu, Jochen Fiebig, Martin Peterlechner, Simon Trubel, Matthias Wegner, Zhan Peng Jin, Gerhard Wilde, Sergiy V. DivinskiAbstract:Abstract Grain Boundary Diffusion of 44 Ti and 63 Ni in the B2 Ti−50.2 at.% Ni polycrystalline alloy was measured in Harrison's B regime (573−923 K) using the radiotracer technique. The triple product P = sδD gb ( s is the segregation factor, δ the Grain Boundary width, and D gb the corresponding Grain Diffusion coefficient) for Ti and Ni was determined. Although the absolute values of the triple products P are typical for the B2-ordered alloys, both Ti and Ni GB Diffusion in NiTi reveals a unique behavior with significant deviations from a linear Arrhenius-type temperature dependence. Transmission electron microscopy analysis of GB structures at 673 K and 923 K substantiated the occurrence of different interface types which may provide the slower and faster Grain Boundary Diffusion paths in agreement with the experimental data. The influence of different types of precipitates on Grain Boundary Diffusion and possible Diffusion mechanisms in the different regimes are discussed.
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Recent Advances and Unsolved Problems of Grain Boundary Diffusion
Defect and Diffusion Forum, 2011Co-Authors: Sergiy V. Divinski, B. S. BoksteinAbstract:Some unresolved problems of Grain Boundary Diffusion – restrictions of Fisher-Gibbs model, refinement of the conditions for B- and C-regimes, relation between segregation (s) and enrichment (b) coefficients, Grain Boundary width, non-linear segregation effects on Grain Boundary Diffusion – are discussed.
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Systematics of Grain Boundary Diffusion and Solute Segregation in Copper Poly- and Bicrystals
Defect and Diffusion Forum, 2008Co-Authors: Sergiy V. DivinskiAbstract:Recent results on radiotracer Grain Boundary Diffusion of different solutes in the same high-purity polycrystalline copper are reviewed. The measurements were performed in extended temperature intervals satisfying Harrison’s B and C regime conditions at higher and lower temperatures, respectively. In the B regime, the triple product P = sδDgb was determined, while the Grain Boundary diffusivity Dgb was directly measured in the C regime (s is the segregation factor and δ the Grain Boundary width). Consequently, the segregation of different solutes in the copper matrix was determined for the true dilute limit conditions. The results on Grain Boundary Diffusion and segregation are analysed in relation to the solute – solvent binding and solute – vacancy interaction in the bulk and in the Grain boundaries. By increasing amount of the applied radiotracer the effect of solute concentration on Grain Boundary Diffusion can thoroughly be examined. Grain Boundary Diffusion experiments on well-characterised bicrystals have been shown to be most suitable for such a study. In a radiotracer experiment, the complete solute segregation isotherm can be measured beginning already from a dilute solution in both, bulk and Grain Boundary.
Katsuyo Thornton - One of the best experts on this subject based on the ideXlab platform.
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theory of Grain Boundary Diffusion induced by the kirkendall effect
Applied Physics Letters, 2008Co-Authors: Huichia Yu, Katsuyo ThorntonAbstract:A set of coupled Diffusion equations is numerically solved to demonstrate that Grain Boundary Diffusion is significantly enhanced when diffusing atomic species have dissimilar atomic hop frequencies in the bulk. The model is based on a rigorous treatment of two-component substitutional Diffusion where vacancies are treated as an additional species. By examining the concentration fields and the eigenvalues of the diffusivity matrix, the origin of the enhanced Grain Boundary Diffusion is explained in terms of the Kirkendall effect.
Richard A. Yund - One of the best experts on this subject based on the ideXlab platform.
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Oxygen Grain Boundary Diffusion in natural and hot-pressed calcite aggregates
Earth and Planetary Science Letters, 1998Co-Authors: John R. Farver, Richard A. YundAbstract:Abstract Oxygen Grain Boundary Diffusion rates were experimentally determined in natural (Solnhofen limestone) and hot-pressed calcite aggregates at 300 to 500°C and 100 MPa water pressure. The Solnhofen limestone was pre-annealed for 24 h at 700°C and 100 MPa confining pressure under anhydrous conditions to produce an equilibrium microstructure for the Diffusion experiments. The synthetic calcite aggregates were formed by hot isostatic pressing of an intimate mixture of 1–2 μm calcite Grains plus 5 wt% 0.3 μm alumina Grains at 700°C and 200 MPa for 3–10 days. Values for the product of the Grain Boundary Diffusion coefficient ( D ′) and the effective Grain Boundary Diffusion width ( δ ) were determined from 18 O concentration profiles measured with an ion microprobe. There is no measurable difference between D ′ δ values obtained for pre-annealed Solnhofen samples and hot-pressed calcite aggregates; the temperature dependence for oxygen Grain Boundary Diffusion at 100 MPa is described by the Arrhenius parameters D 0 ′ δ =3.8×10 −14 m 3 /s and Q =127±17 kJ/mol. Comparison of the results of this study with previously published data show that the rate of oxygen Grain Boundary Diffusion in calcite aggregates is four to five orders of magnitude greater than that of volume Diffusion in calcite single crystals, and the activation energy is less. Grain Boundary Diffusion of oxygen in calcite aggregates is five to six orders of magnitude greater than that of calcium, when the latter is extrapolated to the temperature range of this study. In addition, oxygen Grain Boundary Diffusion rates in calcite aggregates are about a factor of 4–10 and ∼100 times greater than that in feldspar and quartz aggregates, respectively, under similar experimental conditions.
Jens Ribbe - One of the best experts on this subject based on the ideXlab platform.
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Grain Boundary Diffusion of 59Fe in high-purity copper
Acta Materialia, 2019Co-Authors: Jens Ribbe, Vladimir A. Esin, Sergiy V. DivinskiAbstract:Grain Boundary Diffusion of iron in high purity polycrystalline copper is measured using the radiotracer technique and applying the 59Fe isotope. At lower temperatures, K, the measurements are performed under Harrison's C-type kinetic regime and the Grain Boundary Diffusion coefficient of Fe in Cu. Unconventional penetration profiles are measured for Fe Grain Boundary Diffusion in Cu at higher temperatures ( 949 K) under the intended B-type kinetic regime, in fact formal C-type profiles are systematically observed instead. Molecular dynamics simulation with the literature Finnis-Sinclair type interatomic potentials [Ackland et al., Phil. Mag. A, 1997] discovered an unexpected response of Cu Grain boundaries on a partial Fe coverage at temperatures above 900 K. A model of Fe penetration in polycrystalline Cu in such conditions is proposed, which explains the untypical shape of the penetration profiles. The combination of the B- and C-type Grain Boundary Diffusion measurements predict a strong segregation of Fe in Cu with a low segregation enthalpy.
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Grain Boundary Diffusion of 59Fe in high-purity copper
Acta Materialia, 2019Co-Authors: Jens Ribbe, Vladimir A. Esin, Sergiy V. DivinskiAbstract:Abstract Grain Boundary Diffusion of iron in high purity polycrystalline copper is measured using the radiotracer technique and applying the 59Fe isotope. At lower temperatures, T 949 K, the measurements are performed under Harrison's C-type kinetic regime and the Grain Boundary Diffusion coefficient of Fe in Cu, D gb , is determined, D gb = 5.6 ⋅ 10 − 6 × exp ( − 121 kJmol − 1 / R T ) m2/s. Unconventional penetration profiles are measured for Fe Grain Boundary Diffusion in Cu at higher temperatures ( ≥ 949 K) under the intended B-type kinetic regime, in fact formal C-type profiles are systematically observed instead. Molecular dynamics simulation with the literature Finnis-Sinclair type interatomic potentials [Ackland et al., Phil. Mag. A, 1997] discovered an unexpected response of Cu Grain boundaries on a partial Fe coverage at temperatures above 900 K. A model of Fe penetration in polycrystalline Cu in such conditions is proposed, which explains the untypical shape of the penetration profiles. The combination of the B- and C-type Grain Boundary Diffusion measurements predict a strong segregation of Fe in Cu with a low segregation enthalpy.
Vladimir V. Popov - One of the best experts on this subject based on the ideXlab platform.
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Determination of Grain Boundary Diffusion Parameters Based on Specified Model of Grain Boundary Diffusion and Combined Analysis of Radiotracer and Mössbauer Spectroscopy Data
Diffusion Foundations, 2015Co-Authors: Vladimir V. Popov, A. V. SergeevAbstract:The classical Fisher model of Grain-Boundary Diffusion and the traditional method of determination of Grain-Boundary Diffusion parameters by radiotracer technique combined with the serial-sectioning method are analyzed. The Fisher model specification based on the data of the emission Mossbauer spectroscopy is considered, and the additional information which can be extracted from the Mossbauer studies is discussed. The possibility of determination of Grain-Boundary Diffusion parameters based on the combined analysis of the radiotracer technique and Mossbauer spectroscopy with the application of the specified Fisher model of Grain-Boundary Diffusion is considered. This approach is demonstrated by an example of determination of Grain-Boundary Diffusion of Co in W and Mo.
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Investigation of Grain-Boundary Diffusion of Co in Mo by Radiotracer Method and Mössbauer Spectroscopy
Defect and Diffusion Forum, 2015Co-Authors: Vladimir V. Popov, A. V. Sergeev, A. Yu. IstominaAbstract:Grain Boundary Diffusion of Co in Mo has been studied by radiotracer analysis and emission Mossbauer spectroscopy. The experimental results are treated based on the specified Fisher model. The mechanism of Grain Boundary Diffusion of Co in Mo and temperature dependences of segregation factor and Grain Boundary diffusivity have been determined.
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Determination of Grain Boundary Diffusion Parameters Based on Combined Analysis of Radiotracer Technique and Mössbauer Spectroscopy Data
Defect and Diffusion Forum, 2012Co-Authors: Vladimir V. PopovAbstract:A method of Grain Boundary Diffusion characterization has been suggested based on combined analysis of radiotracer serial-sectioning technique and Mossbauer spectroscopy data and a specified model of Grain Boundary Diffusion. Its application for determination of parameters of Co Grain Boundary Diffusion in W is demonstrated.
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Modern Models of Grain Boundary Diffusion
Defect and Diffusion Forum, 2011Co-Authors: Vladimir V. PopovAbstract:Recent models of Grain-Boundary Diffusion are briefly reviewed. Models of Diffusion along equilibrium boundaries of recrystallization origin in coarse-Grained materials and along non-equilibrium boundaries in nanocrystalline materials obtained by gas condensation and compacting or by severe plastic deformation are considered separately.
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Mössbauer Investigations of Grain-Boundary Diffusion and Segregation
Defect and Diffusion Forum, 2006Co-Authors: Vladimir V. PopovAbstract:Possibilities of Grain-Boundary Diffusion and segregation studies using nuclear gammaresonance spectroscopy (NGR) are considered. It is shown that the results of the Mossbauer investigations testify the necessity to specify the classical Fisher’s model of Grain-Boundary Diffusion, and a possible way of such specification is suggested. It is demonstrated that investigation of Grain boundaries using emission Mossbauer spectroscopy appreciably supplement the information obtained from the Diffusion profiles analysis. In particular, Mossbauer investigations make it possible to evaluate directly the Grain-Boundary segregation factor, to determine the Grain-Boundary Diffusion mechanism, to estimate the rate of the diffusant pumping from a Grain Boundary core into the bulk, etc.
