scholarly journals Entropy-Driven Grain Boundary Segregation: Prediction of the Phenomenon

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1331
Author(s):  
Pavel Lejček ◽  
Siegfried Hofmann
Keyword(s):  
Grain Boundary ◽  
Boundary Segregation ◽  
Indirect Evidence ◽  
Solute Segregation ◽  
Grain Boundary Segregation ◽  
Segregation Energy ◽  
Iron Based ◽  
Positive Segregation

The question is formulated as to whether entropy-driven grain boundary segregation can exist. Such a phenomenon would be based on the assumption that a solute can segregate at the grain boundary sites that exhibit positive segregation energy (enthalpy) if the product of segregation entropy and temperature is larger than this energy (enthalpy). The possibility of entropy-driven grain boundary segregation is discussed for several model examples in iron-based systems, which can serve as indirect evidence of the phenomenon. It is shown that entropy-driven grain boundary segregation would be a further step beyond the recently proposed entropy-dominated grain boundary segregation as it represents solute segregation at “anti-segregation” sites.

An atom probe tomography study of grain boundary segregation in nanocrystalline Ni-W

2005 ◽  
Vol 903 ◽  
Author(s):  
Andrew Detor ◽  
Michael K. Miller ◽  
Christopher A. Schuh
Keyword(s):  
Grain Boundary ◽  
Atom Probe Tomography ◽  
Boundary Segregation ◽  
Atom Probe ◽  
Solute Segregation ◽  
Grain Boundary Segregation ◽  
Distribution Analysis ◽  
Grain Sizes ◽  
Composition Fluctuations ◽  
20 Nm

AbstractAtom probe tomography is used to observe the solute distribution in electrodeposited nanocrystalline Ni-W alloys with three different grain sizes (3, 10, and 20 nm) and the results are compared with atomistic computer simulations. The presence of grain boundary segregation is confirmed by detailed analysis of composition fluctuations in both experimental and simulated structures, and its extent quantified by a frequency distribution analysis. In contrast to other nanocrystalline alloys, the present Ni-W alloys exhibit only a subtle amount of solute segregation to the intergranular regions. This finding is consistent with quantitative predictions for these alloys based upon a thermodynamic model of grain boundary segregation.

scholarly journals The role of grain boundary character in solute segregation and thermal stability of nanocrystalline Pt–Au

Nanoscale ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 3552-3563
Author(s):  
Christopher M. Barr ◽  
Stephen M. Foiles ◽  
Malek Alkayyali ◽  
Yasir Mahmood ◽  
Patrick M. Price ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Grain Boundary ◽  
Boundary Segregation ◽  
Solute Drag ◽  
Solute Segregation ◽  
Grain Boundary Segregation ◽  
Grain Boundary Character ◽  
Service Conditions ◽  
Thermal Stability Of

In nanocrystalline alloys, the anisotropy in grain boundary segregation and its impact on dynamic solute drag plays a key role in the thermal stability of these systems during processing treatments or under service conditions.

Influence of grain boundary segregation on diffusion of atoms within grain boundaries of copper based systems

2020 ◽  
pp. 7-11
Author(s):  
V. V. Kulagin ◽  
◽  
A. A. Itskovich ◽  
A. O. Rodin ◽  
B. S. Bokshtein ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Diffusion Process ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Molecular Statics ◽  
Segregation Energy ◽  
Statics And Dynamics

The influence of the segregation energy on the diffusion of second-component atoms in copper is studied by molecular statics and dynamics methods. A number of modified potential is considered. The segregation energy of atoms in a grain boundary is calculated. The number of second-component atoms involved in a diffusion process is found to decrease because of desorption, which leads to a decrease in the grainboundary diffusion coefficient.

Anisotropic Grain Boundary Segregation in Y-Doped TiO2

2001 ◽  
Vol 7 (S2) ◽  
pp. 280-281
Author(s):  
G. D. Lian ◽  
A. Susalla ◽  
E. C. Dickey
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Level Structure ◽  
Boundary Segregation ◽  
Solute Segregation ◽  
Grain Boundary Segregation ◽  
Boundary Misorientation ◽  
Mole Percent ◽  
Dielectric System ◽  
Grain Boundary Misorientation

A variety of properties of polycrystalline TiO2, such as conductivity, creep and grain boundary diffusion, are strongly dependent on the atomic-level structure and chemistry of grain boundaries. TiO2 has been studied as a model dielectric system because of its relatively simple structure and well-understood point defect chemistry. Defect segregation in grain boundaries of polycrystalline and bi-crystal TiO2 have been studied by several groups and significant variations in solute segregation levels from boundary to boundary were observed. in this paper, we address this issue of anisotropic grain boundary segregation. We have measured solute segregation as a function of grain boundary misorientation to determine any correlation between segregation and misorientation.Yttria-doped TiO2 polycrystalline samples were prepared by mixing 99.999% pure TiO2 powder with 0.1% mole percent 99.99% purity Y(NO3)3 (both powders are commercially available from Aldrich Co. or Alfa Co.), followed by uni-axial pressed to 200-400Pa and sintering at 1300 °C for about 5-7 hours.

Investigations on Grain Boundary Segregation Energy of Phosphorus in 12Cr1MoV Steel Under Elastic Stress

2015 ◽  
Vol 18 (4) ◽  
pp. 506-510 ◽  
Author(s):  
Lei Zheng ◽  
Yudong Fu ◽  
Pavel Lejček ◽  
Shenhua Song ◽  
Guido Schmitz ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Elastic Stress ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Segregation Energy

Grain boundary segregation in metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1204-1205
Author(s):  
C.L. Briant
Keyword(s):  
Fracture Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Material Properties ◽  
Electron Spectroscopy ◽  
High Vacuum ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Local Concentration ◽  
The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

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