ASTM E1508-98

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact
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Designation: E 1508 – 98
AMERICAN SOCIETY FOR TESTING AND MATERIALS
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Guide for
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Quantitative Analysis by Energy-Dispersive Spectroscopy
This standard is issued under the fixed designation E 1508; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope beam in the specimen. It covers a range of energies up to the
energy of the electron beam.
1.1 This guide is intended to assist those using energy-
3.2.4 critical excitation voltage—the minimum voltage re-
dispersive spectroscopy (EDS) for quantitative analysis of
quired to ionize an atom by ejecting an electron from a specific
materials with a scanning electron microscope (SEM) or
electron shell.
electron probe microanalyzer (EPMA). It is not intended to
3.2.5 dead time—the time during which the system will not
substitute for a formal course of instruction, but rather to
process incoming X rays (real time less live time).
provide a guide to the capabilities and limitations of the
3.2.6 k-ratio—the ratio of background-subtracted X-ray
technique and to its use. For a more detailed treatment of the
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intensity in the unknown specimen to that of the standard.
subject, see Goldstein, et al. This guide does not cover EDS
3.2.7 live time—the time that the system is available to
with a transmission electron microscope (TEM).
detect incoming X rays.
1.2 This standard does not purport to address all of the
3.2.8 overvoltage—the ratio of accelerating voltage to the
safety problems, if any, associated with its use. It is the
critical excitation voltage for a particular X-ray line.
responsibility of the user of this standard to establish appro-
3.2.9 shaping time—a measure of the time it takes the
priate safety and health practices and determine the applica-
amplifier to integrate the incoming charge; it depends on the
bility of regulatory limitations prior to use.
time constant of the circuitry.
2. Referenced Documents
3.2.10 spectrum—the energy range of electromagnetic ra-
diation produced by the method and, when graphically dis-
2.1 ASTM Standards:
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played, is the relationship of X-ray counts detected to X-ray
E 3 Methods of Preparation of Metallographic Specimens
3
energy.
E 7 Terminology Relating to Metallography
4
E 673 Terminology Relating to Surface Analysis
4. Summary of Practice
E 691 Practice for Conducting an Interlaboratory Study to
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4.1 As high-energy electrons produced with an SEM or
Determine the Precision of a Test Method
EPMA interact with the atoms within the top few micrometres
3. Terminology of a specimen surface, X rays are generated with an energy
characteristic of the atom that produced them. The intensity of
3.1 Definitions—For definitions of terms used in this guide,
such X rays is proportional to the mass fraction of that element
see Terminologies E 7 and E 673.
in the specimen. In energy-dispersive spectroscopy, X rays
3.2 Definitions of Terms Specific to This Standard:
from the specimen are detected by a solid-state spectrometer
3.2.1 accelerating voltage—the high voltage between the
that converts them to electrical pulses proportional to the
cathode and the anode in the electron gun of an electron beam
characteristic X-ray energies. If the X-ray intensity of each
instrument, such as an SEM or EPMA.
element is compared to that of a standard of known composi-
3.2.2 beam current—the current of the electron beam mea-
tion and suitably corrected for the effects of other elements
sured with a Faraday cup positioned near the specimen.
present, then the mass fraction of each element can be
3.2.3 Bremsstrahlung—background X rays produced by
calculated.
inelastic scattering (loss of energy) of the primary electron
5. Significance and Use
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This guide is under the jurisdiction of ASTM Committee E-4 on Metallography
5.1 This guide covers procedures for quantifying the el-
and is the direct responsibility of Subcommittee E04.11 on X-Ray and Electron
Metallography. emental composition of phases in a microstructure. It includes
Current edition approved October 10, 1998. Published December 1998. Origi-
both methods that use standards as well as standardless
nally published as E 1508 – 93. Last previous edition E 1508 – 93a.
methods, and it discusses the precision and accuracy that one
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Goldstein, J. I., Newbury, D. E., Echlin, P., Joy, D. C., Romig, A. D., Jr., Lyman,
can expect from the technique. The guide applies to EDS with
C. D., Fiori, C., and Lifshin, E., Scanning Electron Microscopy and X-ray
Microanalysis, 2nd ed., Plenu
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