The characteristics of the interlayers in metal matrix composites strongly influence the materials properties. We have investigated the formation of such layers in carbon-fibre reinforced Mg-Al alloys, produced via a gas-pressure melt-infiltration process. Results of high-voltage electron microscopy, high-resolution electron microscopy, selected area diffraction and electron energy loss spectroscopy with analysis of near-edge fine structures (ELNES) of the relevant ionization edges (Mg-L-23, Al-L-23, C-K, Mg-K and Al-K) revealed that ternary carbides of approximate composition Al2MgC2 formed at the fibre/matrix interfaces. Analyses of ELNES point to a close relationship in terms of crystal chemistry between the ternary carbide Al2MgC2 and the binary carbide Al4C3. For Al2MgC2, a structure is proposed, with metal atoms in a close-packed arrangement filled with carbon atoms in octahedral and trigonal-bipyramidal interstices. [References: 26]

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