Grain boundary segregation in [100] symmetrical tilt bicrystals of an FeSi alloy

Hofmann, S.; Lejěek, P.; Adámek, J.

doi:10.1002/sia.7401901112

Cited by 36 publications

(27 citation statements)

References 24 publications

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“…Recently the segregation of Si, P, and C was simultaneously measured at various well-characterized grain boundaries in bicrystals of an a-Fe base multicomponent alloy by Auger electron spectroscopy [11][12][13]. From the temperature dependences of the boundary composition, the segregation enthalpies and entropies were determined according to equation (13) assuming wl = wM and saturation coverage to be unity, and considering site competition effects.…”

Section: Grain Boundary Segregation Diagramsmentioning

confidence: 99%

“…From the temperature dependences of the boundary composition, the segregation enthalpies and entropies were determined according to equation (13) assuming wl = wM and saturation coverage to be unity, and considering site competition effects. In addition, mutual interactions of segregants were involved on the basis of Guttmann's theory of segregation in multicomponent systems (equation (2)) [8].…”

Section: Grain Boundary Segregation Diagramsmentioning

confidence: 99%

“…In these diagrams, the segregation enthalpies AH] of the solutes I for pure binary systems were used to describe the dependence of the segregation on solid solubility in a-iron and on boundary orientation. The experiments suggest the possibility of expressing this dependence as a sum of two independent terms [11][12][13].…”

Section: Introductionmentioning

confidence: 98%

“…Therefore AH] is an independent, fundamental characteristic of the segregation of solute I in matrix M. From this point of view the tendency of a solute to segregate at grain boundaries is better characterized by more fundamental thermodynamic quantities such as the segregation enthalpy as compared to the enrichment ratio [10]. Recently, the first experimentally determined segregation diagrams were constructed from measured solute segregation at well-characterized grain boundaries in [100] tilt bicrystals of an Fe-3.5 at % Si alloy containing traces of phosphorus and carbon [11][12][13]. In these diagrams, the segregation enthalpies AH] of the solutes I for pure binary systems were used to describe the dependence of the segregation on solid solubility in a-iron and on boundary orientation.…”

Section: Introductionmentioning

confidence: 99%

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Grain boundary segregation diagrams of α-iron

Lejček

Hofmann

1993

Interface Sci

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Based on thermodynamic analysis of interracial segregation, the segregation enthalpy AH ~ of a solute I in a given matrix was found to depend linearly on two mutually independent terms reflecting the type of interface 9 and the solid solubility limit X~ at temperature T and can be written as AH~ X;) = AH*(~) + vR[Tln(X;)]In this equation, the structural dependence of interfacial segregation is contained in AH*(~) which corresponds to the extrapolated segregation enthalpy of a solute with unlimited solubility in the matrix. The product [T ln(X~)] is essentially constant with temperature, and can therefore be obtained from data for maximum solid solubility, [T In(X~)]mas. The parameter v > 0 represents the relationship between the activity a} of a solute at the bulk solid solubility limit in a given matrix and X~, a} -(X~) ", and is characteristic for the matrix. Using recent experimental data for silicon, phosphorus, and carbon segregation at well-characterized grain boundaries in oriented bicrystals of a-iron, the averaged value = 0.77 was determined. Values of AH*(4~) range from -8 kJ/mol (general grain boundaries) up to +8 kJ/mol (special grain boundaries). These values are discussed and used for a more precise and generalized construction of grain boundary segregation diagrams of oL-iron.

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Section: Grain Boundary Segregation Diagramsmentioning

confidence: 99%

Section: Grain Boundary Segregation Diagramsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Grain boundary segregation diagrams of α-iron

Lejček

Hofmann

1993

Interface Sci

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“…The temperature dependence of the segregation factor of Au in Cu leads to the Arrhenius parameters s 0 0X88 and H s À9X7 kJamol on the condition of Henrytype segregation behaviour. Hofmann et al [21] studied the orientation dependence of GB segregation enthalpies of Si, P and C in symmetrical [001] Fe± 3.5% Si tilt GBs. The smallest values of H s are observed at symmetrical GBs of high coincidence.…”

Section: Estimation Of the Structure Dependence Of Au Gb Segregation mentioning

confidence: 99%

Tracer diffusion of Au and Cu in a series of near Σ=5 (310)[001] symmetrical Cu tilt grain boundaries

et al. 1999

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AbstractÐGrain boundary diusion of Au and Cu was measured in a series of Cu bicrystals with symmetrical near AE 5, Â 36X98 310001 CSL tilt grain boundaries (GBs) using the radiotracer and the serial sectioning technique. The orientations of the bicrystals were very precisely determined with the Kossel technique where all three macroscopic parameters describing the orientations of the grains in the bicrystal were evaluated. The tilt angles ranged from 33.218 to 39.268. The GB diusion of the radiotracers 195 Au and 64 Cu was measured as a function of tilt angle and temperature. In the investigated temperature range 1030±661 K the orientation dependence of both radiotracers shows a characteristic cusp not exactly at but slightly below the ideal AE 5 CSL GB. The Arrhenius parameters, activation enthalpy and frequency factor, determined from lower temperature data adopt a maximum, again slightly before the ideal AE 5 CSL GB. These features are discussed with respect to the accidental small twist and second tilt orientations and the corresponding dislocation network inherent in the investigated real GBs. With increasing temperature a negative deviation from a straight Arrhenius behaviour is observed. This result indicates a certain change in the GB structure in the temperature range above 800 K. #

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Role of entropy in anistropy of grain boundary segregation

Lejček

1998

Surf. Interface Anal.

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From the viewpoint of existence of linear dependence between entropy and enthalpy of grain boundary segregation, the meaning of the entropy term is discussed. It is suggested that negative values of segregation entropy for silicon segregation at individual grain boundaries in α‐iron reflect an ‘ordering’ tendency of the interfaces due to the presence of silicon. On the other hand, positive values of segregation entropy suggest a ‘disordering’ of the structure of these grain boundaries by segregation of carbon and mainly of phosphorus. The effect of ‘disordering’ is especially high for special grain boundaries with compact intrinsic structure, resulting in high values of segregation entropy. The slope of the dependence of enthalpy on entropy of solute segregation at different grain boundaries can be considered as a compensation temperature. Its existence implies that an anisotropy of grain boundary chemical composition will possess a qualitatively different character above and under this temperature. This anisotropy measured above the compensation temperature will be characterized by high values of grain boundary concentration for special boundaries as compared to general boundaries. © 1998 John Wiley & Sons, Ltd.

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Grain boundary segregation in [100] symmetrical tilt bicrystals of an FeSi alloy

Cited by 36 publications

References 24 publications

Grain boundary segregation diagrams of α-iron

Grain boundary segregation diagrams of α-iron

Tracer diffusion of Au and Cu in a series of near Σ=5 (310)[001] symmetrical Cu tilt grain boundaries

Role of entropy in anistropy of grain boundary segregation

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