FIBRE MATRIX INTERACTIONS IN MAGNESIUM-BASED COMPOSITES CONTAINING ALUMINA FIBERS/

An investigation has been made of composites with magnesium-based matr ices CPMg, AZ61 and AZ91 reinforced with Safimax low-density (LD), sta ndard-density (SD) and RF Saffil alumina fibres, using either a squeez e or a gas-pressure casting route. Detailed investigations of structur al features have been made using SEM, TEM and EDX analysis. The overal l extent of reaction between matrix and fibre was affected by the volu me fraction of fibres and (locally) by the formation of metal channels between fibre bundles. Fibre microstructure and porosity are the key features which significantly influence the extent of chemical interact ion. LD (Safimax) alumina fibres were fully reacted and cannot be empl oyed to produce liquid-metal infiltrated composites, unless a method t o stabilize or protect the fibres can be found. In the case of SD Safi max fibres, the metal/ceramic interaction produced a considerable pene tration of magnesium into the fibres. However, there was negligible ch emical reaction in composites containing RF Saffil alumina fibres.