Interface reactions in squeeze cast Saffil fibre/piston alloy composites

ISSN： 1743-2847

Source： Materials Science and Technology, Vol.14, Iss.1, 1998-01, pp. : 47-53

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Abstract

High resolution scanning transmission electron microscopy techniques were used to analyse the reaction layer formed between the fibre and metal in aluminium alloy metal matrix composites. It was found that the reaction layer formed between the fibre and metal was uniform and that the layer was not affected by the phases present in the adjacent metal. It was also found that the reaction layer was the same irrespective of whether it formed next to a region of binder (SiO₂ or Al.SiO₂) or of fibre (δ-Al₂O₃ or Al.SiO₂). The layer formed with this system is assumed to be MgAl₂O₄. Further experiments were carried out using high spatial resolution Auger spectroscopy. Analysis of samples fractured under ultra high vacuum conditions revealed that the metal/fibre interface fractured at the MgAl₂O₄ layer. The evidence presented strongly suggests that the interface layer wasformed by a reaction between the metal and the atmosphere, rather than by a reaction between the metal and the fibre. It was also shown that the MgAl₂O₄ layer is the weakest point in the interface region.