Silicides powders, properties

It has to be mentioned that the chemical analysis of the impurities often is insufficient for an adequate powder characterisation because of their very specific influence on the properties of the powder compacts (sintered bodies). On the one hand, particle size and particle distribution of the impurity inclusions are important for instance it has been shown that the same impurity contents of Fe cause a drastic decrease in strength of the compacts if concentrated in few inclusions with diameters >50 pm, but have nearly no influence as inclusions <5-10 pm [238]. On the other hand, most metallic impurities form silicides which cause a remarkable volume increase [238]. 

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