The classification of short range order by electron microscopy

After discussion of the various modelling concepts, a broad classification of short range order (sro) is suggested, differentiating between uniform and bounded ‘micro-domains’ and unbounded ‘static concentration wave packets’. It is explained why this classification is physically useful, and how transmission electron microscopy (TEM) imaging provides a direct means of differentiating between these two models. The analogy between this model classification and the microcrystallite-amorphous problem in the classification of ‘glassy’ structures is discussed.Criticisms [1] of our earlier work [2] on electron diffraction information obtained for Ni₄Mo have been carefully analysed. We could find no reason to change our view of the nature of s.r.o. in this particular material. Our essential conclusion is that it is unrealistic to describe sro in quenched Ni₄Mo as of microdomain type.