Investigations into the Microstructures of Carbon Fibre (T 800H)/Magnesium Alloy (AZ91) Composites

摘要

Composites of T 800H carbon fibres and the Magnesium alloy AZ91 were produced by Squeeze Casting. As a result of this method of casting and the presence of the carbon fibres, segregation of the Magnesium alloy occurs whereby an intermetallic zone of Mg_(17)AL_(12) is precipitated around the carbon fibres. Electron beam microscopic investigations confirm the formation of needle-like phases of different morphology at the fibre-matrix interface, which differ from one another in their geometry and orientation. Needle-like phases with a length to diameter ratio L/D of between 4 and 6 are found orientated parallel to the surface of the T 800H fibres, whilst needles with an L/D ratio of between 20 and 25 are found positioned at angles between 45 and 135 deg to the fibre surface.