Recent Developments in the Study of Grain Boundary Segregation by Wavelength Dispersive X-Ray Spectroscopy (WDS)

2011 ◽  
Vol 309-310 ◽  
pp. 39-44
Author(s):  
Pawel Nowakowski ◽  
Frédéric Christien ◽  
Marion Allart ◽  
René Le Gall

It was recently shown [1] that EMPA-WDS (Electron Probe MicroAnalysis by Wavelength Dispersive X-ray Spectroscopy) can be used to detect and to accurately quantify monolayer surface and grain boundary segregation. This paper presents the last developments of this application. It focuses on the measurement of sulphur grain boundary segregation in nickel on fractured surfaces. A special attention was paid to the quantification of the sulphur coverage, taking into account the non-normal incidence of the electron beam on a fracture surface. Sulphur grain boundary segregation kinetics was measured at 750°C in nickel to document the quantitative possibilities of the technique.

Author(s):  
C.L. Briant

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.


2018 ◽  
Vol 54 (14) ◽  
pp. 1417-1420
Author(s):  
S. A. Darznek ◽  
V. B. Mityukhlyaev ◽  
P. A. Todua ◽  
M. N. Filippov

2011 ◽  
Vol 605 (7-8) ◽  
pp. 848-858 ◽  
Author(s):  
P. Nowakowski ◽  
F. Christien ◽  
M. Allart ◽  
Y. Borjon-Piron ◽  
R. Le Gall

2020 ◽  
Vol 326 ◽  
pp. 09001
Author(s):  
Seiichiro Ii ◽  
Toru Hara

We characterized the distribution of minor elements such as Si and Fe in Al utilizing a nanoindentation and electron microscopy with an energy dispersed X-ray spectroscopy (EDS) system. Nanoindentation can detect the dislocation nucleation known as “pop-in” event, the critical load (Pc) depends on the solute amount of Fe. However, that in Si-doped Al is rarely changed up to 1.0 at% of Si. That independent Pc in Al-Si is caused by the inhomogeneity of the Si, which is the grain boundary segregation, in Al. The grain boundary segregation of Si was clearly detected by using a newly developed microcalorimeter type EDS system, even at the 0.1 at% Si.


Author(s):  
K. S. Vecchio

Recently coherent bremsstrahlung (CB) peaks have been detected in x-ray spectra in the analytical electron microscope (AEM). It has been suggested that CB peaks, which are Gaussian, may either mask, or be misinterpreted as elemental peaks in x-ray spectra. A method for identifying and isolating these peaks has been presented, The problem of CB peaks is particularly severe in AEM grain boundary segregation studies, because the amount of segregant in the interaction volume is small (<∼3 wt%), the x-ray counting times are long, and as a result the CB peak intensities can approximate to the expected segregant peak intensity. The misleading effects of CB can be either to produce pseudo-element peaks close to true element peak positions, or to overestimate the true element peak intensity when the CB peaks are superimposed on the x-ray peak of the segregant. This article reports an investigation of the effects of CB on segregation studies in Cu and Fe.


Author(s):  
Ian M. Anderson ◽  
J. Bentley

Multivariate statistical analysis (MSA) of a series of spectra or images offers an objective and quantitative way to characterize the features of the spectra that vary in a correlated fashion and to determine the number of independently varying components in the series. For example, in a series of spectra showing grain boundary segregation, there may be only one independently varying spectral component, which signifies an increase in the concentrations of the segregants and a corresponding decrease in the concentrations of some of the matrix constituents. The basis of the MSA method has been outlined by Trebbia and Bonnet, with application to the analysis of electron energy-loss spectrum images. Titchmarsh et al., have applied this analysis to a series of energy dispersive X-ray (EDX) spectra for the study of grain boundary segregation. The present paper illustrates the application of MSA methods to a series of EDX spectra acquired for ALCHEMI analysis. The basic method has been modified slightly for the analysis of ALCHEMI data.


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