1、BS ISO 24173:2009 ICS 71.040.50 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Microbeam analysis Guidelines for orientation measurement using electron backscatter diffractionThis British Standard was published under the authority of the Standards Policy and
2、Strategy Committee on 31 October 2009 BSI 2009 ISBN 978 0 580 55397 4 Amendments/corrigenda issued since publication Date Comments BS ISO 24173:2009 National foreword This British Standard is the UK implementation of ISO 24173:2009. The UK participation in its preparation was entrusted to Technical
3、Committee CII/9, Microbeam analysis. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a Britis
4、h Standard cannot confer immunity from legal obligations.BS ISO 24173:2009Reference number ISO 24173:2009(E) ISO 2009INTERNATIONAL STANDARD ISO 24173 First edition 2009-09-01 Microbeam analysis Guidelines for orientation measurement using electron backscatter diffraction Analyse par microfaisceaux L
5、ignes directrices pour la mesure dorientation par diffraction dlectrons rtrodiffuss BS ISO 24173:2009 ISO 24173:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typef
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10、www.iso.org Published in Switzerland ii ISO 2009 All rights reservedBS ISO 24173:2009 ISO 24173:2009(E) ISO 2009 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms and definitions .1 4 Equipment for EBSD .7 5 Operating conditions 8 6 Calibrations
11、 required for indexing of EBSPs .13 7 Analytical procedure .16 8 Measurement uncertainty.17 9 Reporting the results 18 Annex A (informative) Principle of EBSD .19 Annex B (normative) Specimen preparation for EBSD.20 Annex C (informative) Brief introduction to crystallography and EBSP indexing, and o
12、ther information useful for EBSD 26 Bibliography42 BS ISO 24173:2009 ISO 24173:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Stan
13、dards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also t
14、ake part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees
15、is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibil
16、ity that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 24173 was prepared by Technical Committee ISO/TC 202, Microbeam analysis. BS ISO 24173:2009 ISO 24173:2009(E) ISO 2009 All rights r
17、eserved vIntroduction Electron backscatter diffraction (EBSD) is a technique that is used with a scanning electron microscope (SEM), a combined SEM-FIB (focussed-ion beam) microscope or an electron probe microanalyser (EPMA) to measure and map local crystallography in crystalline specimens1,2 . Elec
18、tron backscatter patterns (EBSPs) are formed when a stationary electron beam strikes the surface of a steeply inclined specimen, which is usually tilted at 70 from normal to the electron beam. EBSPs are imaged via an EBSD detector, which comprises a scintillator (such as a phosphor screen or a YAG s
19、ingle crystal) and a low-light-level camera (normally a charge-coupled device, CCD). Patterns are occasionally imaged directly on photographic film. By analysing the EBSPs, it is possible to measure the orientation of the crystal lattice and, in some cases, to identify also the phase of the small vo
20、lume of crystal under the electron beam. EBSD is a surface diffraction effect where the signal arises from a depth of just a few tens of nanometres, so careful specimen preparation is essential for successful application of the technique3 . In a conventional SEM with a tungsten filament, a spatial r
21、esolution of about 0,25 m can be achieved; however, with a field-emission gun SEM (FEG-SEM), the resolution limit is 10 nm to 50 nm, although the value is strongly dependent on both the material being examined and on the instrument operating parameters. Orientation measurements in test specimens can
22、 be carried out with an accuracy of 0,5. By scanning the electron beam over a region of the specimen surface whilst simultaneously acquiring and analysing EBSPs, it is possible to produce maps that show the spatial variation of orientation, phase, EBSP quality and other related measures. These data
23、can be used for quantitative microstructural analysis to measure, for example, the average grain size (and in some cases the size distribution), the crystallographic texture (distribution of orientations) or the amount of boundaries with special characteristics (e.g. twin boundaries). EBSD can provi
24、de three-dimensional microstructural characterization by its use in combination with an accurate serial sectioning technique, such as focussed-ion beam milling4 . It is strongly recommended that EBSD users be well acquainted with both the principles of crystallography and the various methods for rep
25、resenting orientations (both of which are described in the existing literature in this field) in order to make best use of the EBSD technique and the data produced5,6 . BS ISO 24173:2009BS ISO 24173:2009 INTERNATIONAL STANDARD ISO 24173:2009(E) ISO 2009 All rights reserved 1Microbeam analysis Guidel
26、ines for orientation measurement using electron backscatter diffraction IMPORTANT The electronic file of this document contains colours which are considered to be useful for the correct understanding of the document. Users should therefore consider printing this document using a colour printer. 1 Sc
27、ope This International Standard gives advice on how to generate reliable and reproducible crystallographic orientation measurements using electron backscatter diffraction (EBSD). It addresses the requirements for specimen preparation, instrument configuration, instrument calibration and data acquisi
28、tion. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO/IEC 17025, Gener
29、al requirements for the competence of testing and calibration laboratories ISO/IEC Guide 98-3, Uncertainty of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1
30、 crystal entity consisting of a regular, repeated arrangement of atoms in space and usually described by a space group, a crystal system, unit cell parameters (including the lengths and angles between the unit cell axes) and the positions of the atoms inside the unit cell7,8NOTE 1 For example, an al
31、uminium crystal can be represented by a cube (unit cell) of length 0,404 94 nm along each edge and with atoms at the corners and centres of the cube faces. NOTE 2 Simulations of the atomic arrangement in a small (4 4 4 unit cells) aluminium crystal, as viewed along the 1 0 0, 1 1 1 and 1 1 0 directi
32、ons, are shown in Figure 1, together with the associated spherical Kikuchi patterns for each crystal orientation. The 4-fold, 3-fold and 2-fold crystal symmetries are easily seen, as are the mirror planes. NOTE 3 For those unfamiliar with crystallography, it is recommended that a standard textbook b
33、e consulted (see for example References 7, 8 and 9). NOTE 4 Annex C contains a brief introduction to crystallography and a guide to the indexing of EBSPs for materials with cubic crystal symmetry. BS ISO 24173:2009 ISO 24173:2009(E) 2 ISO 2009 All rights reservedFigure 1 Simulations of a small alumi
34、nium crystal (top) as viewed along the 1 0 0, 1 1 1 and 1 1 0 directions, with their associated spherical Kikuchi patterns (bottom). The symmetry is clearly shown. 3.2 crystal plane plane, usually denoted as (h k l), representing the intersection of a plane with the a-, b- and c-axes of the unit cel
35、l at distances of 1/h, 1/k and 1/l, where h, k, and l are integers NOTE 1 The integers h, k, and l are usually referred to as the Miller indices of a crystal plane. NOTE 2 See Annex C for more information. 3.3 crystal direction direction, usually denoted as u v w, representing a vector direction in
36、multiples of the basis vectors describing the a, b and c crystal axes NOTE See Annex C for more information. 3.4 crystal unit cell cell which is repeated (infinitely) to build up the crystal NOTE It is usually defined by three lengths, a, b and c, and three angles, , and . The lengths are usually gi
37、ven in ngstrms or nanometres and the angles in degrees. 3.5 crystallographic orientation alignment of the crystal coordinate system (for example, 1 0 0, 0 1 0, 0 0 1 for a cubic crystal) in relation to the specimen coordinate system NOTE The specimen coordinate system can be denoted as X, Y, Z. When
38、 EBSD is applied to the study of rolled materials, it is often denoted as RD, TD, ND RD = reference (or rolling) direction, TD = transverse direction and ND = normal direction. BS ISO 24173:2009 ISO 24173:2009(E) ISO 2009 All rights reserved 33.6 EBSD detector detector used to capture the electron b
39、ackscatter pattern and convert it to an image visible on the display device (computer screen) via a video-camera, which is commonly a high-sensitivity charged-coupled device (CCD) NOTE See also 3.21. 3.7 electron backscatter diffraction EBSD diffraction process that arises between the backscattered
40、electrons and the atomic planes of a highly tilted crystalline specimen when illuminated by a stationary incident electron beam NOTE Commonly used alternative terms for EBSD are “EBSP” (or more usually the “EBSP technique”) (see 3.8), “BKD” (backscattered Kikuchi diffraction), “BKED” (backscattered
41、Kikuchi electron diffraction) and “BKDP” (backscattered Kikuchi diffraction pattern). 3.8 electron backscatter pattern EBSP intersecting array of quasi-linear features, known as Kikuchi bands (see Figure 2), produced by electron backscatter diffraction and recorded using a suitable detector, for exa
42、mple observed on a phosphorescent screen or, less commonly, on photographic film Figure 2 Examples of EBSPs showing arrays of overlapping Kikuchi bands 3.9 EBSD grain region, with similar orientation, delineated by boundaries at which the misorientation between neighbouring measurement points is gre
43、ater than a defined critical value which depends on the application103.10 EBSD spatial resolution minimum distance between two points in different grains (separated by a sharp boundary) that produces two distinctly different EBSPs that can be correctly indexed using an EBSD system NOTE An example is
44、 shown in Figure 3 where the electron beam has been passed over a boundary in a meteorite specimen. Two distinct and different EBSP orientations can be seen in the far-left and far-right images, but the central EBSP is a mixture of the two. Modern indexing algorithms frequently allow solution of suc
45、h overlapping patterns, which leads to an effective improvement in the EBSD spatial resolution. BS ISO 24173:2009 ISO 24173:2009(E) 4 ISO 2009 All rights reservedFigure 3 Examples of EBSPs from either side (far left and far right) and on a grain boundary (centre) (Note that these images were taken a
46、t 30 nm spacings and the centre EBSP is a combination of the other two) 3.11 Euler angles set of three rotations for representing the orientation of a crystal relative to a set of specimen axes NOTE The Bunge convention (rotations about the Z, X and Z directions) is most commonly used for describing
47、 EBSD data. The Euler angles give the rotation needed to bring the specimen coordinate system into coincidence with the crystal coordinate system. It should be noted that there are equivalent sets of Euler angles, depending on crystal symmetry6 . 3.12 Hough transform mathematical technique of image
48、processing which allows the automated detection of features of a particular shape within an image NOTE In EBSD, a linear Hough transform is used to identify the position and orientation of the Kikuchi bands in each EBSP, which enables the EBSP to be indexed. Each Kikuchi band is identified as a maxi
49、mum in Hough space. The Hough transform is essentially a special case of the Radon transform. Generally, the Hough transform is for binary images, and the Radon transform is for grey-level images11,12 . See 5.3.7 for more details. 3.13 indexing process of identifying the crystallographic orientation corresponding to the features in a given EBSP, for example determining which crystal planes correspond to the detected Kikuchi bands or which crystal direction
