ISO 19214-2017 Microbeam analysis - Analytical electron microscopy - Method of determination for apparent growth direction of wirelike crystals by transmission .pdf

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1、 ISO 2017 Microbeam analysis Analytical electron microscopy Method of determination for apparent growth direction of wirelike crystals by transmission electron microscopy Analyse par microfaisceaux Microscopie lectronique analytique Mthode de dtermination de la direction apparente de croissance des

2、cristaux filiformes par microscopie lectronique en transmission INTERNATIONAL STANDARD ISO 19214 First edition 2017-04 Reference number ISO 19214:2017(E) ISO 19214:2017(E)ii ISO 2017 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in Switzerland All rights reserved. Unless other

3、wise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address b

4、elow or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO 19214:2017(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T

5、erms and definitions . 1 4 Specimens 2 5 Analysis procedure . 2 5.1 Setting the TEM operating condition . 2 5.1.1 Preparation of the TEM 2 5.1.2 Accelerating voltage 2 5.1.3 Setting the specimen 2 5.1.4 Calibration of the rotation angle 2 5.2 Data acquisition . 3 5.2.1 Select the target crystal 3 5.

6、2.2 Obtaining diffraction patterns . 3 5.2.3 Determining interplanar spacing 4 5.2.4 Index diffraction patterns 4 5.2.5 Non-uniqueness of the indexing result 5 5.3 Determination of the crystalline direction . 5 5.3.1 General approach 5 5.3.2 Simplified procedure for special situations 8 5.3.3 Conver

7、t the crystallographic index 8 5.3.4 Result of the multiplicity factor 9 6 Uncertainty estimation 9 7 Test report 10 Annex A (informative) Relationships of Miller notation and Miller-Bravais notation for hexagonal crystals 11 Annex B (informative) Matrix G and G -1for the crystal systems 12 Annex C

8、(informative) Example of a test report .14 Bibliography .15 ISO 2017 All rights reserved iii Contents Page ISO 19214:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Internation

9、al Standards 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,

10、 also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part

11、 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives). Attention is drawn to the possibility that some of t

12、he 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. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations

13、received (see www .iso .org/ patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity asses

14、sment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: w w w . i s o .org/ iso/ foreword .html. This document was prepared by Technical Committee ISO/TC 202, Microbeam analysis, Subcommittee

15、SC 3, Analytical electron microscopy.iv ISO 2017 All rights reserved ISO 19214:2017(E) Introduction Wirelike crystals (including beltlike crystals) are a main component in some advanced materials, especially nanomaterials, and also appear in traditional materials, such as needle-shaped precipitates

16、in steels and alloys. Controlling the microstructure of these materials during fabrication is very important for quality control considerations. To control the microstructure and thereby improve the service properties of the relevant materials, the apparent growth direction or the longest axis of th

17、e wires is one of the essential parameters. This direction is generally determined for wirelike crystals whose diameter or thickness and width is ranged from tens to hundreds of nanometres by transmission electron microscopy (TEM). ISO 2017 All rights reserved v Microbeam analysis Analytical electro

18、n microscopy Method of determination for apparent growth direction of wirelike crystals by transmission electron microscopy 1 Scope This document prescribes a method for the determination of apparent growth direction by transmission electron microscopy. It is applicable to all kinds of wirelike crys

19、talline materials fabricated by various methods. This document can also guide in ascertaining an axis direction of the second-phase particles with a rod-like or polygonal shape in steels, alloys or other materials. The applicable diameter or width of the crystals to be tested is in the range of tens

20、 to hundreds of nanometres, depending on the accelerating voltage of the TEM and the material itself. NOTE In the present document, wirelike crystals, beltlike crystals, needle-shaped second-phase particles, etc. are all subsumed by the broad category of wirelike crystals. 2 Normative references The

21、 following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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.

22、ISO 24173, Microbeam analysis Guidelines for orientation measurement using electron backscatter diffraction ISO 25498:2010, Microbeam analysis Analytical electron microscopy Selected-area electron diffraction analysis using a transmission electron microscope 3 T erms a nd definiti ons For the purpos

23、es of this document, the terms and definitions given in ISO 24173 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at

24、 h t t p :/ www .iso .org/ obp 3.1 wirelike crystal crystal resembling a thread with a diameter or width measuring in nanometres 3.2 apparent growth direction crystalline direction which is parallel to the longest dimension of a single crystal Note 1 to entry: Apparent growth direction does not invo

25、lve mechanisms of the phase interface migration. 3.3 Miller notation indexing system for diffraction patterns, which describes a crystal lattice by three axes coordinate INTERNATIONAL ST ANDARD ISO 19214:2017(E) ISO 2017 All rights reserved 1 ISO 19214:2017(E) 3.4 Miller-Bravais notation indexing sy

26、stem for diffraction patterns of hexagonal crystal, which describes the lattice by four axes coordinate 4 Specimens 4.1 The sample crystals shall be clean, without contamination or oxidation. They are stable under electron beam irradiation during TEM analysis. 4.2 Powder or extracted powder specimen

27、s of the crystals may be analyzed. The sample powder shall be well dispersed by a suitable technique so that individual crystals can be observed under the TEM. NOTE One of the techniques in common use is ultrasonic dispersion. In this method, the sample powder is immersed in ethanol or pure water an

28、d dispersed by ultrasonication for about 0,5 h to 1 h, then dropped onto the supporting film surface of a microgrid. Afterward, the microgrids are dried at room temperature. The wirelike crystals are usually parallel to the supporting film plane. Other techniques to prepare individual crystal specim

29、ens can also be adopted, depending upon the physical characteristics of the sample 2 . 4.3 The precipitates or second-phase particles in steels, alloys and the like may be extracted, then treated as powder specimens; see 4.2. 4.4 Thin-foil specimens of various solid substances prepared by suitable m

30、ethods are applicable. The specimen shall be thin enough to transmit the electron beam 3 . 5 Analysis procedure 5.1 Setting the TEM operating condition 5.1.1 Preparation of the TEM The TEM working condition shall comply with ISO 25498:2010, 8.1. 5.1.2 Accelerating voltage The applicable accelerating

31、 voltage of the TEM for the analysis mainly depends upon the thickness of the specimen to be studied. Stability of the crystals under electron beam irradiation is also important for the accelerating voltage setting. As long as the structure and/or morphology of the specimen are not altered during th

32、e analysis, clear images and sharp diffraction patterns can be obtained on the TEM. The corresponding accelerating voltage or higher may be suitable for the work. 5.1.3 Setting the specimen Place the specimen to be tested firmly in the double-tilting or tilting-rotation specimen holder, then insert

33、the holder into the specimen chamber. It is recommended to use the cold finger of TEM before conditioning. 5.1.4 Calibration of the rotation angle As specified in ISO 25498:2010, 8.1.6, to be able to successfully correlate the axis of interest in an image with the corresponding diffraction pattern,

34、the rotation angle between the micrograph and its corresponding diffraction pattern may need to be calibrated. A molybdenum trioxide crystal specimen 2 ISO 2017 All rights reserved ISO 19214:2017(E) may be used as a reference for the rotation angle calibration. The analyst may refer to textbooks suc

35、h as References 4 and 5 for the experimental procedure for this calibration. NOTE For some transmission electron microscopes, the rotation angle has been compensated by the manufacturer. In this case, step 5.1.4 can be ignored. 5.2 Data acquisition 5.2.1 Select the target crystal On the viewing scre

36、en, TV monitor, or computer screen of the TEM, get an overview image of the specimen in low magnification mode. Select an individual crystal which is clean and free from damage or distortion as the target. Under bright-field imaging mode, adjust the magnification to get a clear magnified image of th

37、e target crystal. Adjust the specimen height (Z axis) to the eucentric position. Focus the image. 5.2.2 Obtaining diffraction patterns 5.2.2.1 General Various electron diffraction techniques may be applicable for determination of the crystal axis direction. The selected area electron diffraction (SA

38、ED) and microbeam diffraction techniques are in common use; however, for the present purpose, the spot diffraction patterns or the patterns formed by the incident beam through a small angle aperture are preferred. 5.2.2.2 Procedure The procedure for taking diffraction patterns and images of the targ

39、et crystal is as follows. a) Select a suitable position of the target crystal in the specimen and select a diffraction mode (SAED, microdiffraction, or other suitable mode). Switch to the diffraction mode to get a spot diffraction pattern. Tilt the specimen slightly so that the brightness distributi

40、on on the diffraction pattern is symmetrical and a zero-order Laue zone pattern is displayed. Therefore, the zone axis, Z 1(with index u 1 v 1 w 1 ), of this diffraction pattern is nearly reverse parallel to the incident beam direction, B. Record this diffraction pattern, Z 1,and take note of the re

41、ading on the X and Y tilting angle of the double tilting specimen stage as X 1and Y 1,respectively. Refer to the instruction manual provided by the microscope manufacturer for the operation procedure for each diffraction mode. b) Switch back to the imaging mode without changing the specimen orientat

42、ion to get a correlative bright field image, M 1 , of the target crystal. Check the focus of this image and take a photo or save it in the computer system. This image, M 1,is formed under the incident beam direction, B 1 , which is approximately reversely parallel to the zone axis, Z 1 . c) Return t

43、o the diffraction mode and tilt the specimen to produce a second diffraction pattern with zone axis Z 2 . Record this diffraction pattern, Z 2 , and take note of the reading on the X and Y tilt angle of the specimen holder as X 2and Y 2 , respectively. d) Repeat step b) to form the second bright fie

44、ld image, M 2 , of the target crystal. This image, M 2 , is formed under the incident beam direction, B 2 , which is nearly reversely parallel to the zone axis, Z 2 , of the specimen. e) The angle, , between the two specimen holder positions (that is, the angle * between the zone axis, Z 1 , with in

45、dex u 1 v 1 w 1 and Z 2 , with index u 2 v 2 w 2 ) can be obtained from the differences between the readings on the X and Y tilting angles at each position (see ISO 25498:2010, 8.2). ISO 2017 All rights reserved 3 ISO 19214:2017(E) 5.2.3 Determining interplanar spacing To determine the interplanar s

46、pacing, d hkl , of the plane (hkl) in crystals, the simplified Bragg law, as shown in Formula (1), shall be followed. R hkl d hkl= L (1) whereL is the camera length; is the wavelength of the incident electron beam;L is the camera constant;R hkl is the distance between the central spot and the diffra

47、cted spot of crystalline plane (hkl) in the diffraction pattern. When the camera constant L is known, the interplanar spacing d hklcan be found, in principle, using Formula (1) by measuring the distance R hkl . However, in practice, 2R hkl(the distance between the spots hkl and ) shall be measured,

48、then divided by two to calculate the distance R hkl . In most cases, the camera constant, L, shall be calibrated for the present work. The practical procedure for camera constant calibration is specified in ISO 25498:2010, 8.3. Camera constant, L, calibration is usually performed by using a referenc

49、e specimen such as polycrystalline pure gold or pure aluminium. At a given accelerating voltage, record the ring diffraction pattern of the reference specimen. Index the diffraction rings and measure the diameters 2R hklof the corresponding ring (hkl), respectively. Find the interplanar spacing d hklfor plane (hkl) of the reference specimen by the crystallographic formulae. The diffraction constant, L, can then be calculated using Formula (1). In practice, either the L D/2 plot or an average value of