ISO 19214:2017
(Main)Microbeam analysis — Analytical electron microscopy — Method of determination for apparent growth direction of wirelike crystals by transmission electron microscopy
Microbeam analysis — Analytical electron microscopy — Method of determination for apparent growth direction of wirelike crystals by transmission electron microscopy
ISO 19214:2017 prescribes a method for the determination of apparent growth direction by transmission electron microscopy. It is applicable to all kinds of wirelike crystalline 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 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.
Analyse par microfaisceaux — Microscopie électronique analytique — Méthode de détermination de la direction apparente de croissance des cristaux filiformes par microscopie électronique en transmission
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INTERNATIONAL ISO
STANDARD 19214
First edition
2017-04
Microbeam analysis — Analytical
electron microscopy — Method of
determination for apparent growth
direction of wirelike crystals by
transmission electron microscopy
Analyse par microfaisceaux — Microscopie électronique analytique
— Méthode de détermination de la direction apparente de croissance
des cristaux filiformes par microscopie électronique en transmission
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms 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
5.2.2 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 Convert 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
-1
Annex B (informative) Matrix G and G for the crystal systems .12
Annex C (informative) Example of a test report .14
Bibliography .15
Foreword
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This document was prepared by Technical Committee ISO/TC 202, Microbeam analysis, Subcommittee
SC 3, Analytical electron microscopy.
iv © ISO 2017 – All rights reserved
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
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 the
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).
INTERNATIONAL STANDARD ISO 19214:2017(E)
Microbeam analysis — Analytical electron 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 crystalline 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 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 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.
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 Terms and definitions
For the purposes 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 http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// 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 involve mechanisms of the phase interface migration.
3.3
Miller notation
indexing system for diffraction patterns, which describes a crystal lattice by three axes coordinate
3.4
Miller-Bravais notation
indexing system 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 specimens 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 and 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
[2]
specimens can also be adopted, depending upon the physical characteristics of the sample .
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 methods are applicable. The
[3]
specimen shall be thin enough to transmit the electron beam .
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 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 the 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 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, the rotation angle between the micrograph and i
...
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