1、Designation: E7 15E7 17Standard Terminology Relating toMetallography1This standard is issued under the fixed designation E7; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates
2、 the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This standard covers the definition of terms, acronyms, and symbols used in ASTM d
3、ocuments related to the field ofmetallography and metallographic testing. Terms that are only relevant to a particular standard or that are adequately defined ina general dictionary are not defined in this terminology standard.1.2 This standard includes terminology used in metallographic areas, such
4、 as, but not limited to: light microscopy,microindentation hardness testing, specimen preparation, x-ray and electron metallography, quantitative metallography,photomicrography, and determination of grain size and inclusion content.1.3 This standard may be of use to individuals utilizing standards o
5、f Committee E04 as well as by those in need of a generalreference source for terminology in the field of metallography.2. Referenced Documents2.1 ASTM Standards:2E45 Test Methods for Determining the Inclusion Content of SteelE80 Recommended Practice for Dilatometric Analysis of Metallic Materials; R
6、eplaced by E 228 (Withdrawn 1986)3E112 Test Methods for Determining Average Grain SizeE1122 Practice for Obtaining JK Inclusion Ratings Using Automatic Image Analysis (Withdrawn 2006)33. Significance and Use3.1 Standards of Committee E04 consist of test methods, practices, and guides developed to en
7、sure proper and uniform testingin the field of metallography. In order for one to properly use and interpret these standards, the terminology used in these standardsmust be understood.3.2 The terms used in the field of metallography have precise definitions. The terminology and its proper usage must
8、 becompletely understood in order to adequately communicate in this field. In this respect, this standard is also a general source ofterminology relating to the field of metallography facilitating the transfer of information within the field.4. Terminologyabsorptionthe decrease in intensity which ra
9、diation undergoes during its passage through matter when the ratio of transmittedor reflected luminous flux to incident is less than 1.absorption coefficientspecific factor characteristic of a substance on which its absorption radiation depends. The rate ofdecrease of the natural logarithm of the in
10、tensity of a parallel beam per unit distance traversed in a substance. For X-rays, thelinear absorption coefficient is the natural logarithm of the ratio of the incident intensity of an X-ray beam incident on unitthickness of an absorbing material to the intensity of the beam transmitted. If Ieis th
11、e incident intensity of a beam of X-rays,Itthe transmitted intensity, and X the thickness of the absorbing material, then:It 5Ieexp2X! (1)Here is the linear absorption coefficient. The mass absorption coefficient is given by / where is the density.1 This terminology is under the jurisdiction of ASTM
12、 Committee E04 on Metallography and are the direct responsibility of Subcommittee E04.02 on Terminology.Current edition approved June 1, 2015June 1, 2017. Published July 2015July 2017. Originally approved in 1926. Last previous edition approved 20142015 as E7 14. 15.DOI: 10.1520/E0007-15.10.1520/E00
13、07-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard
14、 is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommen
15、ds that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1absorption edgean
16、 abrupt change in absorption coefficient at a particular wavelength. The absorption coefficient is always largeron the short wavelength side of the absorption edge.absorption limitSee absorption edge.acceleratingpotentiala relatively high voltage applied between the cathode and anode of an electron
17、gun to accelerate electrons.achromaticliterally, color-free.Alens or prism is said to be achromatic when corrected for two colors. The remaining color seenin an image formed by such a lens is said to be secondary chromatic aberration. See apochromatic objectiveachromatic objectivean objective that i
18、s corrected chromatically for two colors, and spherically for one, usually in theyellow-green part of the spectrum.achromatic objective lensan objective lens with longitudinal chromatic correction for green and blue, and spherical chromaticcorrection for green. NoteLens should be used with a green f
19、ilter.acid extractionSee extraction.air-lockan intermediate enclosed chamber of a vacuum or pressure system through which an object may be passed withoutmaterially changing the vacuum or pressure of the system.alignmenta mechanical or electrical adjustment of the components of an optical device in s
20、uch a way that the path of theradiating beam coincides with the optical axis or other predetermined path in the system. In electron optics there are three generaltypes:(1) magnetic alignmentan alignment of the electron optical axis of the electron microscope such that the image rotatesabout a point
21、in the center of the viewing screen when the current flowing through a lens is varied.(2) mechanical alignmenta method of aligning the geometrical axis of the electron microscope by relative physicalmovement of the components, usually as a step preceding either magnetic or voltage alignment.(3) volt
22、age alignmenta condition of alignment of an electron microscope such that the image expands or contractssymmetrically about the center of the viewing screen when the accelerating voltage is changed.allotriomorphic crystala crystal whose lattice structure is normal, but whose outward shape is imperfe
23、ct since it is determinedto some extent by the surroundings; the grains in a metallic aggregate are allotriomorphic crystals.alloy systema complete series of compositions produced by mixing in all proportions any group of two, or more, components,at least one of which is a metal.alpha brassa solid s
24、olution phase of one or more alloying elements in copper and having the same crystal lattice as copper.alpha iron (Fe)solid phase of pure iron which is stable at temperatures below 910C and possesses the body-centered cubiclattice. It is ferro-magnetic below 768C.amplifiera negative lens, used in li
25、eu of an eyepiece, to project under magnification the image formed by an objective. Theamplifier is especially designed for flatness of field and should be used with an apochromatic objective.ampliphan eyepiece See amplifier.analyzeran optical device, capable of producing plane polarized light, used
26、 for detecting the state of polarization.angle of reflection: ( 1)reflection the angle between the reflected beam and the normal to the reflecting surface.(2) diffractionthe angle between the diffracted beam and the diffracting planes.Angstrom unit (abbreviation) = A, , orA. Ua unit of length equal
27、to 108 cm. This is the standard unit of measurement in X-raycrystallography.angular apertureSee aperture, optical.anisotropic (replaces anisotropy)having different values for a property, in different directions.annealing-twin bands See twin bands.anode apertureSee aperture.anvilthe base on which obj
28、ects for hardness test are placed.anvil effectthe effect caused by use of too high a load or when testing the hardness of too thin a specimen, resulting in a bulgeor shiny spot on the under side of the specimen.aperture, electron:anode aperture the opening in the accelerating voltage anode shield of
29、 the electron gun through which the electrons must passto illuminate or irradiate the specimen.condenser aperturean opening in the condenser lens controlling the number of electrons entering the lens and the angularaperture of the illuminating beam. The angular aperture can also be controlled by the
30、 condenser lens current.E7 172physical objective aperturea metal diaphragm, centrally pierced with a small hole, used to limit the cone of electrons acceptedby the objective lens. This improves image contrast since highly scattered electrons are prevented from arriving at the Gaussianimage plane and
31、 therefore can not contribute to background fog.aperture, opticalthe working diameter of a lens or a mirror.angular aperture the angle between the most divergent rays which can pass through a lens to form the image of an object.aperture diaphragma device to define the aperture.apochromatic objective
32、an objective with longitudinal chromatic correction for red, green and blue, and spherical chromaticcorrection for green and blue. This is the best choice for high resolution or color photomicrography.arcingin electron diffraction, the production of segments of circular patterns, indicating a depart
33、ure from completely randomorientation of the crystals of the specimen.arrestthat portion of a cooling curve in which temperature is invariant with time (for example, thermal or eutectic arrest).artifacta false microstructural feature that is not an actual characteristic of the specimen; it may be pr
34、esent as a result ofimproper or inadequate preparation, handling methods, or optical conditions for viewing.ascending fork pointin a ternary phase diagram, the configuration at the convergence of the three bivariant curves upon eachof the four phases associated in Class II univariant equilibrium; fo
35、r example, the union of two ascending liquidus surface valleysto form one ascending liquidus surface valley.aspect ratiothe length-to-width ratio of a microstructural feature in a two-dimensional plane.asterisma lengthening of diffraction spots usually in the radial direction.astigmatisma defect in
36、a lens or optical system which causes rays in one plane parallel to the optical axis to focus at a distancedifferent from those in the plane at right angles to it.ASTM grain size number See grain size.athermalnot isothermal, with changing rather than constant temperature conditions.atomic replicaSee
37、 replica.atomic scattering factorthe ratio of the amplitude of the wave scattered by an atom to that scattered by a single electron.Symbol = f.austenitea face-centered cubic solid solution of carbon or other elements in gamma iron.austenite grain sizethe grain size which exists or existed in austeni
38、te at a given temperature. See Test Methods E112.autographic dilatometera dilatometer that automatically records instantaneous and continuous changes in dimensions andsome other controlled variable such as temperature or time.autographic pyrometer See pyrometer.automatic image analysisthe separation
39、 and quantitative evaluation of an image into its elements with or without operatorinteraction. It includes the enhancement, detection, and quantification of the features contained in an image through the use ofoptical, geometrical, and stereological parameters and a computer program. Image analysis
40、 data output can provide individualmeasurements on each separate feature (feature specific) or totals for all features of a particular type in the field (field specific).automatic image analyzera device which can be programmed to detect and measure features of interest in an image. It mayinclude acc
41、essories such as automatic focus and an automatic traversing stage to permit unattended operation.average coefficient of cubical expansion average change in unit volume of a substance per unit change in temperature over aspecified range of temperature.average coefficient of linear expansion average
42、change in unit length of a body per unit change in temperature over a specifiedrange of temperature.average coefficient of thermal expansion general term. (See also average coefficient of cubical expansion and averagecoefficient of linear expansion.)average grain diameter See grain size.axial ratiot
43、he ratio of the length of one axis to that of another (for example, c/a) or the continued ratio of three axes (forexample, a:b:c).axis (crystal)the edge of the unit cell of a space lattice. Any one axis of any one lattice is defined, in length and direction, withrespect to the other axes of that lat
44、tice.E7 173Babos lawthe vapor pressure over a liquid solvent is lowered approximately in proportion to the quantity of a nonvolatile solutedissolved in the liquid.backing filma film used as auxiliary support for the thin replica or specimen-supporting film.back reflectionthe diffraction of X-rays at
45、 a Bragg angle approaching 90.bainiteupper, lower, intermediate metastable microstructure or microstructures resulting from the transformation ofaustenite at temperatures between those which produce pearlite and martensite. These structures may be formed on continuous(slow) cooling if the transforma
46、tion rate of austenite to pearlite is much slower than that of austenite to bainite. Ordinarily, thesestructures may be formed isothermally at temperatures within the above range by quenching austenite to a desired temperatureand holding for a period of time necessary for transformation to occur. If
47、 the transformation temperature is just below that atwhich the finest pearlite is formed, the bainite (upper bainite) has a feathery appearance. If the transformation temperature isjust above that at which martensite is produced, the bainite (lower bainite) is acicular, resembling slightly tempered
48、martensite.At the higher resolution of the electron microscope, upper bainite is observed to consist of plates of cementite in a matrix offerrite. These discontinuous carbide plates tend to have parallel orientation in the direction of the longer dimension of the bainiteareas. Lower bainite consists
49、 of ferrite needles containing carbide platelets in parallel array cross-striating each needle axis atan angle of about 60. Intermediate bainite resembles upper bainite; however, the carbides are smaller and more randomlyoriented.bandin electron diffraction, a broad intensity maximum with sharp edges.banded structure (banding)alternate bands parallel with the direction of working resulting from the elongation of segregatedareas.barrel distortion See distortion.basal planethat plane of a hexagon
