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ISO 11938-2012 pdf free download
ISO 11938-2012 pdf free download.Microbeam analysis — Electron probe microanalysis — Methods for elementalmapping analysis using wavelengthdispersive spectroscopy
Analyse par micro faisceaux — Analyse par microsonde électronique (microsonde de Castaing) — Méthodes danalyse par cartographie élémen faire en utilisant Ia spec frométrie a dispersion de Ion gueur d’onde.
One need measure only selected elements of interest rather than all of the elements present In the specimen. This method can be used as a first-step analysis to give an Indication of what more detailed analysis might be required, for example to indicate qualitatively the degree of heterogeneity, or the number of phases, present in the specimen.
The limitations of this method are that, since no matrix correchons are carried out, background levels and absorption, fluorescence and atomic-number effects might produce apparent variations in the element maps which do not reflect the true element variations, An example is given in Annex A. Partial correction may be carried out by acquiring element background maps and subtracting these from the respective element peak maps, but this will still not compensate for absorption or fluorescence effects.
NOTE It is not necessary to subtract the background intensity.
5.3 k-value method
When using the k-value method, the measured raw X-ray intensity at each pixel is divided by the intensity value of a stored reference material. After adjusting for the concentration of the element in the reference material, the resulting values are displayed as the element map. Where possible, the X-ray intensity values for both the specimen and the reference material shall be corrected for background.
As with the raw-intensity method, this is a quick and simple method of analysis and does not require all the elements in the specimen to be measured. It can be used as a qualitative first-step analysis, or for beam- sensitive specimens where only single mapping runs can be carried out.
The limitations are also similar to the raw-intensity method, since only a crude correction is carried out. Absorption, fluorescence and atomic-number effects are not corrected for, so this method could lead to misinterpretation of the element distributions.
5.4 Calibration curve method
In the calibration curve method, a series of reference materials with the same matrix as the specimen and encompassing the range of compositions in the specimen is used to generate a correction curve. The curve Is used to convert the measured raw intensities into quantitative ratios on the plotted map.
The main benefits of this method are its speed and simplicity, since there is no computational overhead for quantification because no background or matrix corrections are needed as these are automatically compensated for by the reference materials. Analysis times can be further reduced by measuring only selected elements of interest rather than all of the elements present in the specimen. Also, the counting statistics can be relatively poor and stilt produce a visible element distribution. The main limitations are that it is generally restricted to the study of binary and ternary systems and requires an appropriate range of reference materials, as shown In ISO 16592.ISO 11938-2012 pdf free download.
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