GB/T 43883-2024Microbeam analysis - Analytical electron microscopy - Method for determining the number density of nanoparticles in a metal (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1:1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting: Please note that some of the contents of this document may involve patents: The issuing organization of this document does not assume the responsibility for identifying patents: This document was proposed and coordinated by the National Microbeam Analysis Standardization Technical Committee (SAC/TC38): This document was drafted by: AECC Beijing Research Institute of Aeronautical Materials, University of Science and Technology Beijing, and Oxford Instruments Technology (Shanghai) Co:, Ltd: The main drafters of this document: Lou Yanzhi, Liu Delu and Xu Ningan:

Nanoscale second phase particles dispersed in metal materials have an important influence on the microstructure and mechanical properties of the materials: The number density of particles is an important parameter that is indispensable for many materials in performance evaluation and production process improvement: Due to the limitation of resolution, many analytical methods are difficult to observe and count, but transmission electron microscopy can Modern high-resolution techniques such as TEM/STEM are common techniques for nanoparticle analysis: The determination method of the number density of nanoparticles in standard materials is extremely important for the research and development of metal materials and the formulation and improvement of production processes: significance: Microbeam analysis Electron microscopy Metal nanostructures Method for determination of particle number density

1 Scope

GB/T 43883-2024 gives the transmission and scanning transmission electron microscopy method for measuring how many nanoparticles there are per unit volume of a metal. In steels and superalloys the strength comes from precipitates a few nanometres across, and it is their number density, not their size alone, that sets the spacing a dislocation has to pass and therefore the yield strength; the same quantity governs the population of oxide particles in ODS alloys and of irradiation-induced clusters in reactor steels. Counting them is not straightforward, because the micrograph is a projection and the answer depends entirely on how well the specimen thickness is known. The standard sets the principle, the specimen and its TEM or STEM preparation, the instruments, the test method, the determination of the specimen thickness, the calculation of the number density from the count and the thickness, the assessment of the uncertainty, and the test report, with an informative annex on counting particles with image analysis software. It took effect on 1 November 2024.

This document describes the application of transmission electron microscopy/scanning transmission electron microscopy (TEM/STEM) techniques to the determination of nanostructures in metallic materials: Method for the number density of second phase particles at meter scale: This document is applicable to the determination of the number density of second phase particles dispersed in metal materials with a particle size ranging from a few nanometers to tens of nanometers: The average size of the particles to be measured should be less than about 1/3 of the thickness of the TEM sample, and the particles in the sample should not overlap each other in the TEM image: The samples with particle size not in this range can be executed as a reference, and other crystalline materials can be executed as a reference: This method is not suitable for determining the number density of aggregated second phase particles: NOTE

1 The minimum particle size that can be measured depends on the resolution of the TEM/STEM equipment used and the experimental technique employed:

Note 2: The second phase particle size to be measured is usually in the range of 5nm to 40nm:

Note 3: If there is overlap of second phase particles in the TEM image, the uncertainty of particle counting will increase:

2 Normative references

The contents of the following documents constitute the essential clauses of this document through normative references in this document: For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to This document:

GB/T 18907 Microbeam analysis - Electron microscopy - Transmission electron microscopy - Selected area electron diffraction analysis method

GB/T 20724 Microbeam analysis of thin crystal thickness by convergent beam electron diffraction

GB/T 27418 Evaluation and expression of measurement uncertainty

GB/T 40300 Terminology of Microbeam Analysis Electron Microscopy

3 Terms and definitions

The terms and definitions defined in GB/T 40300 and the following apply to this document: 3:1 measurementframe An area on a specimen image where particles are counted and imaged: NOTE: A series of measurement frames constitute the total test area: [Source: GB/T 21649:1-2008, 3:1:2, modified] 3:2 binary imagebinaryimage An image in which each pixel has only two possible values or grayscale levels: 3:3 annular dark-field detector annular dark-field detector ADF detector In STEM, a ring-shaped detector is placed around the direct beam to collect scattered electrons and superimpose their intensities to form a dark field image:

Note: Z-contrast due to Rutherford scattering is obtained at high scattering angles, while ADF dark field images are obtained at low scattering angles: