Grain-Size Determination

The grain size is often determined when the properties of polycrystalline and singlephase materials are under consideration. In this regard, it is important to realize that for each material, the constituent grains have a variety of shapes and a distribution of sizes. Grain size may be specified in terms of average or mean grain diameter, and a number of techniques have been developed to measure this parameter. 

Relationship between ASTM grain size nnmber and nnmber of grains per sqnare inch (at 100 x) 

The rationale behind the assigmnent of the grain-size number to these various charts is as follows Let G represent the grain-size munber, and let n be the average number of grains per square inch at a magnification of lOOx. These two parameters are related to each other through the expression  

For photomicrographs taken at magnifications other than 100 X, use of the following modified form of Equation 4.17 is necessary  

In this expression, Um is the number of grains per square inch at magnification M. In addition, the inclusion of the term makes use of the fact that, whereas magnification is a length parameter, area is expressed in terms of units of length squared. As a consequence, the number of grains per unit area increases with the square of the increase in magnification. 

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LAB IV Laboratory for humus analyses and grain size determinations. To be nominated (suggestion the Netherlands Institute of Applied Geoscience TNO - National Geological Survey). 

However, it is not always possible to clearly reveal the structure of high purity metals by electropolishing alone, even in the most simple case of grain size determination of a recrystallized material. Consequently, electropolishing must... 

McManus, J. M., 1988. Grain size determination and interpretation. In Tucker, M. (ed.) Techniques in Sedimentology. Blackwell Scientific Publications, London 63-85. 

Vander Voort, G.R (1984) Metallography Principles and Practice, McGraw-Hill, New York, p. 435. Currently out of print. Although its title says it is for the metallurgist, it contains a detailed discussion of grain size determination that can be applied equally well to nonmetals. It gives a detailed description of the various methods and their pros and cons. 

Fig. 5.70 Fracture toughness of TZ-3YB ceramic as a function of grain size, determined at different indentation loads [30]. With kind permission of Dr. Trunec...

Fig. 14.6 Influence of MoO contents in Sn02 Mo03 composite on (a) response to consecutive injections (1 pL) of ethanol at 275 and (b) Sn02 grain size determined by TEM (Adapted with permission from Arbiol et al. 2006, Copyright 2006 Elsevier)...

Grain Size Determination from Transmission Electron Microscopy... 

The average grain size determined from the XRD using the Debye-Scherrer equation was 42-46 nm, depending on the reaction conditions. XPS was used to confirm the presence of Ag(0) in the samples by the presence of Ag3ds/2 and Ag3d3/2 peaks. 

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