Non-equilibrium segregation of sulfur due to grain boundaries motions in nickel

The segregation of solute or imparity elements to grain boundaries can occur by three well-defined processes. The first is Gibbsian segregation in which an element of minimal matrix solubility confines itself to a monolayer at the grain boundary. Classical examples include Bi in Cu and S or P in Fe. The second process involves the depletion of excess matrix solute by volume diffusion to the boundary. In the boundary, the solute atoms diffuse rapidly to precipitates, causing them to grow by the ‘collector-plate mechanism.’ Such grain boundary diffusion is thought to initiate “Diffusion-Induced Grain Boundary Migration,” (DIGM). This process has been proposed as the origin of eutectoid transformations or discontinuous grain boundary reactions. The third segregation process is non-equilibrium segregation which result in a solute build-up around the boundary because of solute-vacancy interactions.All of these segregation phenomena usually occur on a sub-micron scale and are often affected by the nature of the grain boundary (misorientation, defect structure, boundary plane).

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Application of analytical electron microscopy to studies of equilibrium and non-equilibrium segregation in materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130705 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1214-1215

Author(s):

Edward A Kenik

Keyword(s):

Electron Microscopy ◽

Analytical Electron Microscopy ◽

Extended Defects ◽

Probe Diameter ◽

Specimen Holder ◽

Analytical Electron ◽

Scanning Transmission ◽

Solute Atoms ◽

Equilibrium Segregation ◽

Non Equilibrium

Segregation of solute atoms to grain boundaries, dislocations, and other extended defects can occur under thermal equilibrium or non-equilibrium conditions, such as quenching, irradiation, or precipitation. Generally, equilibrium segregation is narrow (near monolayer coverage at planar defects), whereas non-equilibrium segregation exhibits profiles of larger spatial extent, associated with diffusion of point defects or solute atoms. Analytical electron microscopy provides tools both to measure the segregation and to characterize the defect at which the segregation occurs. This is especially true of instruments that can achieve fine (<2 nm width), high current probes and as such, provide high spatial resolution analysis and characterization capability. Analysis was performed in a Philips EM400T/FEG operated in the scanning transmission mode with a probe diameter of <2 nm (FWTM). The instrument is equipped with EDAX 9100/70 energy dispersive X-ray spectrometry (EDXS) and Gatan 666 parallel detection electron energy loss spectrometry (PEELS) systems. A double-tilt, liquid-nitrogen-cooled specimen holder was employed for microanalysis in order to minimize contamination under the focussed spot.

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Direct measurement of non-equilibrium solute segregation to grain boundaries

Scripta Metallurgica ◽

10.1016/0036-9748(69)90072-6 ◽

1969 ◽

Vol 3 (9) ◽

pp. 663-665 ◽

Cited By ~ 7

Author(s):

S.J. Bercovici ◽

P. Niessen ◽

J.J. Byerley

Keyword(s):

Grain Boundaries ◽

Direct Measurement ◽

Solute Segregation ◽

Non Equilibrium

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EFFECT OF SMALL BULK SULFUR CONTENT AND ANNEALING TEMPERATURE ON THE INTERGRANULAR FRACTURING SUSCEPTIBILITY OF METALLIC NICKEL

Surface Review and Letters ◽

10.1142/s0218625x16500505 ◽

2016 ◽

Vol 23 (06) ◽

pp. 1650050 ◽

Cited By ~ 2

Author(s):

BOUTASSOUNA DJAMAL ◽

RENÉ LE GALL ◽

IBEN KHALDOUN LEFKAIER

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Sulfur Content ◽

Auger Spectroscopy ◽

Metallic Nickel ◽

Boundary Equilibrium ◽

Influence Of Temperature On ◽

Sulfide Compound ◽

Equilibrium Segregation

In this paper, we investigate the influence of temperature on the nickel grain boundary equilibrium segregation of sulfur and the resulting intergranular fracturing susceptibility. Auger electron spectroscopy has been used to study equilibrium segregation of sulfur to the grain boundaries of a metallic nickel, with a mass bulk content of 3.6[Formula: see text]ppm in sulfur. Samples were first annealed at adequate temperatures for sufficiently large equilibrium time, and then quenched in water at room temperature. The analysis carried out shows a significant increase of sulfur concentration in the grain boundary with decreasing temperature. However, the sulfur content in the grain boundary shows a drastic shrink at 700[Formula: see text]C. This can be interpreted by the formation of an aggregate sulfide compound in the area of the grain boundaries. At 650[Formula: see text]C, in situ brittle fracture becomes unworkable and only intragranular fractures are observed. Using the results obtained through the investigation of the grain boundaries by Auger spectroscopy, the standard segregation energy is estimated as [Formula: see text].

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An analytical model for non-equilibrium segregation during crystallization

Journal of Crystal Growth ◽

10.1016/j.jcrysgro.2004.07.073 ◽

2004 ◽

Vol 271 (3-4) ◽

pp. 481-494 ◽

Cited By ~ 50

Author(s):

Kenneth A. Jackson ◽

Kirk M. Beatty ◽

Katherine A. Gudgel

Keyword(s):

Analytical Model ◽

Equilibrium Segregation ◽

Non Equilibrium

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