Structure of metallic glasses

In amorphous solids there is a considerable disorder and it is impossible to give a description of their structure comparable to that applicable to crystals. In a crystal indeed the identification of all the atoms in the unit cell, at least in principle, is possible with a precise determination of their coordinates. For a glass, only a statistical description may be obtained to this end different experimental techniques are useful and often complementary to each other. Especially important are the methods based on diffraction experiments only these will be briefly mentioned here. The diffraction pattern of an amorphous alloy does not show sharp diffraction peaks as for crystalline materials but only a few broadened peaks. Much more limited information can thus be extracted and only a statistical description of the structure may be obtained. The so-called radial distribution function is defined as  

Often the reduced radial distribution function G(r) is deduced which is given by  

System Crystalline Atoms NNNa Distance Amorphous Atoms CNb Distance 

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We expect that the resulting yield surface in the case of homogeneous flow should be an unsymmetrical distorted hexagonal Tresca locus involving only the minimum and maximum principal stresses in view of the lack of fine structure of metallic glasses on the atomic scale (McClintock and Argon 1966 Ward 1983). 

H. Masuda, K. Nishio, and N. Babe, Preparation of microporous metal membrane using two-step replication of interconnected structure of porous glass, J. Mater, Sci Lett, 7i 338 (1994). 

Chaudhari, P, and Turnbull, D., Structure and properties of metallic glasses. Science 199, 11 (1978). 

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