In metal matrix composites the adhesion between a ceramic fibre and the metal matrix should be submitted on the atomic scale to physical or chem-ical forces, without forming a reaction zone [1,2]. Only in this case will fibres remain undamaged and a load transformation from the fibre to the matrix take place during composite application. For different metal matrix composites different processing methods have been developed to achieve this inter-face structure. In SiC-fibre reinforced titanium alloys the fibres are protected by a carbon coating [3, 4] and the mechanical properties of the compo-sites remain unchanged as long as the protective coating prevents the reaction of titanium with the fibre surface [4]. In alumina fibre reinforced alumi-nium alloys fibre wetting and adhesion is submitted to atomic forces and can be supported by magnesium segregation in the interface [5, 6]. Magnesium atoms take up vacancy positions in the alumina surface, reducing the wetting angle during melt infiltration [6]. Thermal loading of these composites results in a fibre-matrix reaction that leads to a fibre and composite strength degradation [5, 6].
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