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The nominal composition of each specimen was also included ast, reference. The operator must also be aware of the possibility of spurious X rays from parts of the chamber, polishing compound elements, or from adjacent phases or a combination thereof.
Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. Both sets of data are reported, and the standardized operating asgm are listed in Table 1.
The two elements need not be in the same specimen. Even though one cannot see the individual components of a peak envelope in a spectrum, there are computer methods of deconvolution. The result is a peak at 1. If the specimen is tilted such that the beam is not perpendicular to the specimen surface, an effective take-off angle asttm used.
It was not possible to specify all of these conditions because some are inherent to asym system used. In many cases, the results are similar, and the standardless method may be used for convenience.
For example in silicates, analyzing silicon and multiplying by the gravimetric factor for SiO2 2. Although results of the standardless analyses were rather good on the Type stainless steel, they may be considerably inferior on other types of specimens.
Practice E is used to analyze the round-robin data for consistency and calculates intralaboratory repeatability and interlaboratory reproducibility statistics. For the alloy MAthe average was 3. More accurate interaction volumes can be computed by Monte Carlo computer methods to generate random electron trajectories, but Eq 1 provides a reasonable estimate for most purposes. It should also be of similar composition and thickness between the standards and the unknowns.
The count rate incident on an X-ray detector is directly proportional to the size of the solid angle de? Both specimens were analyzed by various metal producers, EDS system manufacturers, and one university. Additionally, in the windowless mode any light, such as from cathodoluminescence, can be picked up by the crystal and will contribute to the overall noise of the system.
Standard Guide for Quantitative Analysis by Energy-Dispersive Spectroscopy
Whichever method is used, all elements present must be speci? On the MA alloy, the reproducibility among laboratories was much less than that of the standards technique R in Table 4. For a more detailed treatment of the subject, see Goldstein, et al. For the Type stainless steel, the average error was 0. Some manganese was also present, but because its Ka line overlaps the Cr Kb it was not required to be reported, although some participants did.
Accordingly, most operators choose a 0—10 keV display at higher display resolution rather than a 0—20 keV display at lower resolution. It covers a range of energies up to the energy of the electron beam.
Standardless methods were about equivalent to those using standards for this specimen. This method is not based on any model and, therefore, is more general. Observing the high-energy cutoff of the continuum, as noted in 8.
Each of the specimens was analyzed with a lithium-drifted silicon detector using a set of standardized operating parameters after an initial round-robin wherein parameters were selected by each participant. The compositions of both alloys, as determined by wet chemical analysis, are given in Table 2. Some sources of bias that are under operator control are as follows. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Clearly, for a given overall counting time, the relative precision associated with major elements is greater than for minor or trace elements, insofar as there are necessarily fewer counts in minor peaks. Guidelines are given in Methods E 3. The actual accelerating voltage of the electron beam does not always correspond with the voltage selected on the instrument.
Nevertheless, metals do not make good standards for nonmetals, and vice versa. Heavy metals such as gold that are often used for SEM imaging are less suitable because they heavily absorb X rays; if the coating is thick enough, X-ray lines from those metals will be seen in the spectrum. The inherent precision of the EDS method is controlled by counting statistics. A true mass total, as in analysis against standards, provides information about the quality of the analysis.
ASTM E – 12 Standard Guide for Quantitative Analysis by Energy-Dispersive Spectroscopy
A spectrum of X rays generated by electrons interacting with the specimen contains a background consisting of continuum X rays, often called Bremsstrahlung. E11508 intensity of such X rays is proportional to the mass fraction of that element in the specimen. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters.
The coatings are usually applied in thicknesses of several tens of nanometres. Last previous edition approved in as E — For example, trace element analysis is sensitive to background subtraction because the computer is looking for a small peak above the continuum.
Or, if the standardless technique is used, then a pure net intensity is required. It is not intended ashm substitute for a formal course of instruction, but rather to provide a guide to the capabilities and 1e508 of the technique and to its use.
To ensure reproducible results, calibration should be checked periodically. The differences in the results each produces are usually much less than the precision of the analysis. There are several expressions in use by commercial atsm to calculate this, and all produce similar results if the tilt angle is not extreme.
Requiring set parameters had little effect on the repeatability but improved the reproducibility for chromium and iron, but not for nickel. However, most matrix correction programs are sufficiently accurate to permit the use of pure element standards. Tables of X-ray energies can be found in various texts, such as Goldstein, et al2 or Johnson and White.
It may be that differences in background adtm, peak deconvolution method, matrix correction, and possibly geometric con?