X-ray diffraction and microstructure of slags

Regourd (R34) reviewed structural and other aspects of slags. XRD patterns show an asymmetric, diffuse band from the glass peaking at about 31 20 (CuK d = 0.29 nm) and extending from about 20 to about 37 and a weaker band at about 48 20 (0.19 nm). Crystalline phases, if present in sufficient quantity, give superimposed, sharper peaks melilite and merwinite are the most usual. Neither periclase nor lime is found and, since it is present either in the glass or in these inert, crystalline phases, MgO is not a potential cause of expansion, as it may be in a clinker (S89). 

Some workers using small angle X-ray scattering and light and electron microscopy have found evidence of phase separation within the glass (S90.R34) but others have concluded that this does not occur (U16) slag glasses may vary in this respect. 

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