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David N. Seidman - One of the best experts on this subject based on the ideXlab platform.
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Solute-Atom Segregation At Internal Interfaces
Mrs Bulletin, 2013Co-Authors: S.m. Foiles, David N. SeidmanAbstract:In an alloy, the equilibrium composition in the vicinity of an inhomogeneity, such as a surface or a grain boundary, will generally differ from the composition in the bulk. This was first recognized by Gibbs. This change in local composition can potentially affect the structure and mechanical properties of the boundary. As an example, experiments by Sass and co-workers have shown that the Burgers vector of the dislocations present in Fe-Au twist boundaries depends on the Au concentration at the boundary. This demonstrates that the structure does, in fact, depend on the local composition of the alloy at the interface.This article presents computer simulation studies of equilibrium segregation in binary alloys at grain boundaries, and two experimental studies of interfaces using Atom-probe field-ion-microscopy (APFIM). These studies address two fundamental questions: What is the composition of the boundary region as a function of the bulk composition and temperature? What is the spatial distribution of the two species in the boundary? Note, that the comparison of experiment and calculations, where possible, is crucial. Such comparisons can provide guidance in the experimental analysis, and the comparison also provides a stringent test of the reliability of the simulation methods.This article first describes simulation and Atom-probe field-ion microscope techniques and next discusses the segregation in Ni-Cu alloys to isolated edge dislocations. This is followed by a study of segregation at twist boundaries in Pt-Au alloys. Then, the segregation at an asymmetric mixed tilt-twist boundary in a Pt-Ni alloy is computed, and the results are compared with experimental Atom-probe held-ion-microscopy results. Finally, the results of an Atom-probe study of two-dimensional Re segregation at a twist boundary with a small tilt component in a W-Re alloy are presented.
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Solute Atom segregation to 110 symmetric tilt grain boundaries
Acta Materialia, 1997Co-Authors: J.d. Rittner, David N. SeidmanAbstract:Abstract Segregation of substitutional, oversized Solute Atoms to both equilibrium and metastable structures of twenty-one 〈110〉 symmetric tilt grain boundaries (GBs) in an f.c.c. binary alloy is investigated with Atomistic simulations. The Monte Carlo technique is employed to determine the interfacial excess and the Solute distribution in GB structures for a bulk Solute concentration of 4 at.%. Results from these simulations are used to demonstrate the shortcomings of simple geometric GB parameters for predicting variations in the interfacial excess from GB to GB. The interfacial excess is also found to vary from one structure to another for the same GB. An example of a segregation-induced congruent GB phase transition is also presented. Accurate segregation free energies for individual sites in GBs are calculated with the overlapping distributions Monte Carlo technique. Segregation entropies are determined and are found to be a linear function of the segregation internal energies for the same GB sites.
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Solute-Atom segregation to 〈110〉 symmetric tilt grain boundaries
Acta Materialia, 1997Co-Authors: J.d. Rittner, David N. SeidmanAbstract:Abstract Segregation of substitutional, oversized Solute Atoms to both equilibrium and metastable structures of twenty-one 〈110〉 symmetric tilt grain boundaries (GBs) in an f.c.c. binary alloy is investigated with Atomistic simulations. The Monte Carlo technique is employed to determine the interfacial excess and the Solute distribution in GB structures for a bulk Solute concentration of 4 at.%. Results from these simulations are used to demonstrate the shortcomings of simple geometric GB parameters for predicting variations in the interfacial excess from GB to GB. The interfacial excess is also found to vary from one structure to another for the same GB. An example of a segregation-induced congruent GB phase transition is also presented. Accurate segregation free energies for individual sites in GBs are calculated with the overlapping distributions Monte Carlo technique. Segregation entropies are determined and are found to be a linear function of the segregation internal energies for the same GB sites.
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Solute Atom segregation at high angle 002 twist boundaries in dilute au pt alloys
Journal of Materials Research, 1995Co-Authors: D. Udler, David N. SeidmanAbstract:Solute-Atom segregation is studied by Monte Carlo simulations for three high-angle symmetrical (002) twist boundaries in Au-1 at. % Pt and Pt -1 at. % Au alloys at T = 850 K. It complements our previous study, that focused mainly on low-angle boundaries in the same alloys. Solute enhancement occurs on the Pt-rich side of the phase diagram, while on the Au-rich side net depletion in Solute is observed. Following the trend observed for low-angle boundaries, Au as a Solute prefers the structural units of the perfect crystal type, while Pt as a Solute is depleted at those sites. The Solute concentration at structural units depends on the planar fraction of those units in the boundary.
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Solute Atom segregation structure relations at high angle 002 twist boundaries in dilute ni pt alloys
Interface Science, 1995Co-Authors: D. Udler, David N. SeidmanAbstract:Monte Carlo simulations, utilizing embedded Atom method (EAM) potentials, are employed to investigate in detail Solute-Atom segregation behavior at high-angle symmetrical (002) twist boundaries, at T=850 K, in Pt-3 at.% Ni and Ni-3 at.% Pt alloys. Solute enhancement in those alloys occurs on both sides of the phase diagram, although it is considerably higher on the Ni-rich side. The distributions of Solute concentrations within the first and the second planes are very inhomogeneous, with the sites highly enhanced in Solute being in the minority. The remaining sites exhibit little or no enhancement. The highest level of Solute concentrations at individual sites continues to increase with the value of the rotations angle, θ, until saturation occurs at about the Σ=5 misorientation. The large differences in concentrations between different types of sites suggest the possibility of an ordered grain-boundary phase. The correlation between the structure and Solute species concentrations in most cases follows the trends observed for low-angle boundaries: Pt as a Solute prefers the structural units of the perfect crystal type, while Ni as a Solute tends to segregate at the filler units associated with the cores of the primary grain boundary dislocations. A strong correlation is observed between the position of a site in the first or second (002) plane and the plane of the interface. Rigid-body translations are detected for two boundaries on the Pt-rich side of the phase diagram. Roughening and possible structural multiplicity occur in the Σ=5 boundary on the Ni-rich side. The same boundary on the Pt-rich side of the phase diagram exhibits a considerable amount of structural and chemical disorder.
J.d. Rittner - One of the best experts on this subject based on the ideXlab platform.
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Solute Atom segregation to 110 symmetric tilt grain boundaries
Acta Materialia, 1997Co-Authors: J.d. Rittner, David N. SeidmanAbstract:Abstract Segregation of substitutional, oversized Solute Atoms to both equilibrium and metastable structures of twenty-one 〈110〉 symmetric tilt grain boundaries (GBs) in an f.c.c. binary alloy is investigated with Atomistic simulations. The Monte Carlo technique is employed to determine the interfacial excess and the Solute distribution in GB structures for a bulk Solute concentration of 4 at.%. Results from these simulations are used to demonstrate the shortcomings of simple geometric GB parameters for predicting variations in the interfacial excess from GB to GB. The interfacial excess is also found to vary from one structure to another for the same GB. An example of a segregation-induced congruent GB phase transition is also presented. Accurate segregation free energies for individual sites in GBs are calculated with the overlapping distributions Monte Carlo technique. Segregation entropies are determined and are found to be a linear function of the segregation internal energies for the same GB sites.
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Solute-Atom segregation to 〈110〉 symmetric tilt grain boundaries
Acta Materialia, 1997Co-Authors: J.d. Rittner, David N. SeidmanAbstract:Abstract Segregation of substitutional, oversized Solute Atoms to both equilibrium and metastable structures of twenty-one 〈110〉 symmetric tilt grain boundaries (GBs) in an f.c.c. binary alloy is investigated with Atomistic simulations. The Monte Carlo technique is employed to determine the interfacial excess and the Solute distribution in GB structures for a bulk Solute concentration of 4 at.%. Results from these simulations are used to demonstrate the shortcomings of simple geometric GB parameters for predicting variations in the interfacial excess from GB to GB. The interfacial excess is also found to vary from one structure to another for the same GB. An example of a segregation-induced congruent GB phase transition is also presented. Accurate segregation free energies for individual sites in GBs are calculated with the overlapping distributions Monte Carlo technique. Segregation entropies are determined and are found to be a linear function of the segregation internal energies for the same GB sites.
D. Udler - One of the best experts on this subject based on the ideXlab platform.
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Solute Atom segregation at high angle 002 twist boundaries in dilute au pt alloys
Journal of Materials Research, 1995Co-Authors: D. Udler, David N. SeidmanAbstract:Solute-Atom segregation is studied by Monte Carlo simulations for three high-angle symmetrical (002) twist boundaries in Au-1 at. % Pt and Pt -1 at. % Au alloys at T = 850 K. It complements our previous study, that focused mainly on low-angle boundaries in the same alloys. Solute enhancement occurs on the Pt-rich side of the phase diagram, while on the Au-rich side net depletion in Solute is observed. Following the trend observed for low-angle boundaries, Au as a Solute prefers the structural units of the perfect crystal type, while Pt as a Solute is depleted at those sites. The Solute concentration at structural units depends on the planar fraction of those units in the boundary.
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Solute-Atom segregation/structure relations at high-angle (002) twist boundaries in dilute Ni−Pt alloys
Interface Science, 1995Co-Authors: D. Udler, D. N. SeidmanAbstract:Monte Carlo simulations, utilizing embedded Atom method (EAM) potentials, are employed to investigate in detail Solute-Atom segregation behavior at high-angle symmetrical (002) twist boundaries, at T =850 K, in Pt-3 at.% Ni and Ni-3 at.% Pt alloys. Solute enhancement in those alloys occurs on both sides of the phase diagram, although it is considerably higher on the Ni-rich side. The distributions of Solute concentrations within the first and the second planes are very inhomogeneous, with the sites highly enhanced in Solute being in the minority. The remaining sites exhibit little or no enhancement. The highest level of Solute concentrations at individual sites continues to increase with the value of the rotations angle, θ, until saturation occurs at about the Σ=5 misorientation. The large differences in concentrations between different types of sites suggest the possibility of an ordered grain-boundary phase. The correlation between the structure and Solute species concentrations in most cases follows the trends observed for low-angle boundaries: Pt as a Solute prefers the structural units of the perfect crystal type, while Ni as a Solute tends to segregate at the filler units associated with the cores of the primary grain boundary dislocations. A strong correlation is observed between the position of a site in the first or second (002) plane and the plane of the interface. Rigid-body translations are detected for two boundaries on the Pt-rich side of the phase diagram. Roughening and possible structural multiplicity occur in the Σ=5 boundary on the Ni-rich side. The same boundary on the Pt-rich side of the phase diagram exhibits a considerable amount of structural and chemical disorder.
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Solute Atom segregation structure relations at high angle 002 twist boundaries in dilute ni pt alloys
Interface Science, 1995Co-Authors: D. Udler, David N. SeidmanAbstract:Monte Carlo simulations, utilizing embedded Atom method (EAM) potentials, are employed to investigate in detail Solute-Atom segregation behavior at high-angle symmetrical (002) twist boundaries, at T=850 K, in Pt-3 at.% Ni and Ni-3 at.% Pt alloys. Solute enhancement in those alloys occurs on both sides of the phase diagram, although it is considerably higher on the Ni-rich side. The distributions of Solute concentrations within the first and the second planes are very inhomogeneous, with the sites highly enhanced in Solute being in the minority. The remaining sites exhibit little or no enhancement. The highest level of Solute concentrations at individual sites continues to increase with the value of the rotations angle, θ, until saturation occurs at about the Σ=5 misorientation. The large differences in concentrations between different types of sites suggest the possibility of an ordered grain-boundary phase. The correlation between the structure and Solute species concentrations in most cases follows the trends observed for low-angle boundaries: Pt as a Solute prefers the structural units of the perfect crystal type, while Ni as a Solute tends to segregate at the filler units associated with the cores of the primary grain boundary dislocations. A strong correlation is observed between the position of a site in the first or second (002) plane and the plane of the interface. Rigid-body translations are detected for two boundaries on the Pt-rich side of the phase diagram. Roughening and possible structural multiplicity occur in the Σ=5 boundary on the Ni-rich side. The same boundary on the Pt-rich side of the phase diagram exhibits a considerable amount of structural and chemical disorder.
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Solute Atom segregation at 002 twist boundaries in dilute nipt alloys structural chemical relations
Acta Metallurgica Et Materialia, 1994Co-Authors: D. Udler, David N. SeidmanAbstract:Abstract Monte Carlo simulations, utilizing embedded Atom method (EAM) potentials, are used to investigate Solute-Atom segregation behavior at symmetrical (002) twist boundaries, at T = 850 K, in Pt-3 at.% Ni and Ni-3 at.% Pt alloys. The results show that, unlike the previously investigated AuPt system, the boundaries are enhanced in Solute Atoms on both sides of the phase diagram. For low-angle boundaries on the Pt-rich side the Atomic sites enhanced in Solute concentration are arranged in hourglass-like structures centered on the square grid of primary grain boundary dislocations. While for the same boundaries on the Ni-rich side the Atomic sites enhanced in Solute concentration are located in bipyramidal regions based on the square cells of the same grain boundary dislocations. Thus, the Atomic sites that are enhanced on one side of the phase diagram are not affected on the other side and vice versa.
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Solute-Atom segregation at (002) twist boundaries in dilute NiPt alloys: Structural/chemical relations
Acta Metallurgica et Materialia, 1994Co-Authors: D. Udler, David N. SeidmanAbstract:Abstract Monte Carlo simulations, utilizing embedded Atom method (EAM) potentials, are used to investigate Solute-Atom segregation behavior at symmetrical (002) twist boundaries, at T = 850 K, in Pt-3 at.% Ni and Ni-3 at.% Pt alloys. The results show that, unlike the previously investigated AuPt system, the boundaries are enhanced in Solute Atoms on both sides of the phase diagram. For low-angle boundaries on the Pt-rich side the Atomic sites enhanced in Solute concentration are arranged in hourglass-like structures centered on the square grid of primary grain boundary dislocations. While for the same boundaries on the Ni-rich side the Atomic sites enhanced in Solute concentration are located in bipyramidal regions based on the square cells of the same grain boundary dislocations. Thus, the Atomic sites that are enhanced on one side of the phase diagram are not affected on the other side and vice versa.
S Kustov - One of the best experts on this subject based on the ideXlab platform.
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non linear anelasticity due to dislocation Solute Atom interactions in solid solutions
Journal of Alloys and Compounds, 2000Co-Authors: G Gremaud, S KustovAbstract:Abstract A theory for the non-linear, strain-amplitude-dependent internal friction (ADIF) in solid solutions due to dislocation–Solute Atom interactions has been developed. The suggested model accounts for different modes of dislocation–Solute Atom interactions: • Solute Atoms, distributed in the dislocation glide plane, represent short-range obstacles for the dislocation motion; • Solute Atoms, situated away from the dislocation glide plane, create diffuse weak long-range elastic stress fields, also impeding dislocation motion. Dislocations overcome localised obstacles under the combined action of the applied stress and thermal energy, whereas diffuse long-range obstacles can be surmounted only athermally. Numerical calculations of the ADIF, strain-amplitude-dependent modulus defect, their ratio, and of the fraction of the athermal ADIF component have been performed. The model predicts a complicated multistage behaviour of the parameters of the non-linear anelasticity in the strain amplitude–temperature–Solute concentration domain which is in excellent agreement with recent experimental data.
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Non-linear anelasticity due to dislocation–Solute Atom interactions in solid solutions
Journal of Alloys and Compounds, 2000Co-Authors: G Gremaud, S KustovAbstract:Abstract A theory for the non-linear, strain-amplitude-dependent internal friction (ADIF) in solid solutions due to dislocation–Solute Atom interactions has been developed. The suggested model accounts for different modes of dislocation–Solute Atom interactions: • Solute Atoms, distributed in the dislocation glide plane, represent short-range obstacles for the dislocation motion; • Solute Atoms, situated away from the dislocation glide plane, create diffuse weak long-range elastic stress fields, also impeding dislocation motion. Dislocations overcome localised obstacles under the combined action of the applied stress and thermal energy, whereas diffuse long-range obstacles can be surmounted only athermally. Numerical calculations of the ADIF, strain-amplitude-dependent modulus defect, their ratio, and of the fraction of the athermal ADIF component have been performed. The model predicts a complicated multistage behaviour of the parameters of the non-linear anelasticity in the strain amplitude–temperature–Solute concentration domain which is in excellent agreement with recent experimental data.
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theory of dislocation Solute Atom interactions in solid solutions and related nonlinear anelasticity
Physical Review B, 1999Co-Authors: G Gremaud, S KustovAbstract:A theory for dislocation-Solute Atom interactions in solid solutions has been developed which allows one to calculate the nonlinear dislocation strain-amplitude-dependent internal friction. The suggested model accounts for different modes of dislocation-Solute Atom interactions: (i) Solute Atoms distributed in the dislocation glide plane interact with the dislocation core and represent short-range obstacles for the dislocation motion; (ii) Solute Atoms situated away from the dislocation glide plane create relatively weak long-range elastic stress fields, also impeding dislocation motion. We assume that dislocations move in a two-component system of obstacles which differ with respect to the thermodynamics of dislocation--point-defect interactions. Namely, dislocations overcome short-range obstacles under the combined action of applied stress and thermal energy, whereas relatively weak long-range obstacles are surmounted athermally. The model predicts a complicated multistage behavior of the nonlinear internal friction in the strain amplitude--temperature--Solute concentration domain, which is in excellent agreement with recent experimental data.
G Gremaud - One of the best experts on this subject based on the ideXlab platform.
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Study of Solute Atom-dislocation interactions in Al–Mg alloys by mechanical spectroscopy
Materials Science and Engineering: A, 2006Co-Authors: M. Atodiresei, G Gremaud, Robert SchallerAbstract:Abstract Internal friction and elastic modulus have been measured as function of temperature, strain amplitude and frequency in Al–Mg solid solutions by means of free-decay and forced oscillation torsion pendula. Samples with 4 at.% of Mg were used. The internal friction spectrum measured in the 100–550 K temperature range was found to be mainly composed of a low temperature background between 100 and 400 K, which does not depend on temperature, but depends markedly on the strain amplitude in the range of 5 × 10−6 to 10−4 and of an internal friction peak (at about 440 K for 1 Hz), which evolves into a rapidly rising background at higher temperature. The mechanical spectroscopy results are discussed in terms of a Solute-dislocation interaction model with variation of the average length of dislocation segments. Furthermore, the activation energies of the peak and high temperature background were found to be close to the activation energy of diffusion of Mg Solute Atoms in aluminium. As a consequence, both components could be interpreted by the high temperature dragging of Mg Solute Atoms by the dislocations.
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non linear anelasticity due to dislocation Solute Atom interactions in solid solutions
Journal of Alloys and Compounds, 2000Co-Authors: G Gremaud, S KustovAbstract:Abstract A theory for the non-linear, strain-amplitude-dependent internal friction (ADIF) in solid solutions due to dislocation–Solute Atom interactions has been developed. The suggested model accounts for different modes of dislocation–Solute Atom interactions: • Solute Atoms, distributed in the dislocation glide plane, represent short-range obstacles for the dislocation motion; • Solute Atoms, situated away from the dislocation glide plane, create diffuse weak long-range elastic stress fields, also impeding dislocation motion. Dislocations overcome localised obstacles under the combined action of the applied stress and thermal energy, whereas diffuse long-range obstacles can be surmounted only athermally. Numerical calculations of the ADIF, strain-amplitude-dependent modulus defect, their ratio, and of the fraction of the athermal ADIF component have been performed. The model predicts a complicated multistage behaviour of the parameters of the non-linear anelasticity in the strain amplitude–temperature–Solute concentration domain which is in excellent agreement with recent experimental data.
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Non-linear anelasticity due to dislocation–Solute Atom interactions in solid solutions
Journal of Alloys and Compounds, 2000Co-Authors: G Gremaud, S KustovAbstract:Abstract A theory for the non-linear, strain-amplitude-dependent internal friction (ADIF) in solid solutions due to dislocation–Solute Atom interactions has been developed. The suggested model accounts for different modes of dislocation–Solute Atom interactions: • Solute Atoms, distributed in the dislocation glide plane, represent short-range obstacles for the dislocation motion; • Solute Atoms, situated away from the dislocation glide plane, create diffuse weak long-range elastic stress fields, also impeding dislocation motion. Dislocations overcome localised obstacles under the combined action of the applied stress and thermal energy, whereas diffuse long-range obstacles can be surmounted only athermally. Numerical calculations of the ADIF, strain-amplitude-dependent modulus defect, their ratio, and of the fraction of the athermal ADIF component have been performed. The model predicts a complicated multistage behaviour of the parameters of the non-linear anelasticity in the strain amplitude–temperature–Solute concentration domain which is in excellent agreement with recent experimental data.
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theory of dislocation Solute Atom interactions in solid solutions and related nonlinear anelasticity
Physical Review B, 1999Co-Authors: G Gremaud, S KustovAbstract:A theory for dislocation-Solute Atom interactions in solid solutions has been developed which allows one to calculate the nonlinear dislocation strain-amplitude-dependent internal friction. The suggested model accounts for different modes of dislocation-Solute Atom interactions: (i) Solute Atoms distributed in the dislocation glide plane interact with the dislocation core and represent short-range obstacles for the dislocation motion; (ii) Solute Atoms situated away from the dislocation glide plane create relatively weak long-range elastic stress fields, also impeding dislocation motion. We assume that dislocations move in a two-component system of obstacles which differ with respect to the thermodynamics of dislocation--point-defect interactions. Namely, dislocations overcome short-range obstacles under the combined action of applied stress and thermal energy, whereas relatively weak long-range obstacles are surmounted athermally. The model predicts a complicated multistage behavior of the nonlinear internal friction in the strain amplitude--temperature--Solute concentration domain, which is in excellent agreement with recent experimental data.