C FIBERS - MG MATRIX COMPOSITES PRODUCED BY SQUEEZE CASTING AND FRICTION STIR PROCESSING: Microstructure & Mechanical Behaviour

peer reviewedMg matrix composites appear as suitable competitors to Al alloys, as they allow for a significant weight reduction while exhibiting potentially comparable mechanical properties. A large variety of processing routes have already been considered for their production, including 'liquid state' processes such as squeeze casting. However these techniques necessitate a very careful control, simultaneously, of the solidification process, the wetting behaviour and the possible interfacial reactions between the reinforcements and the molten metal. And this is more particularly true in the case of Mg matrix composites with carbon fibers reinforcements, as Mg alloys are known to exhibit a poor wetting behaviour on carbon substrates. As a consequence, 'solid state' processing routes such as friction stir processing, that has been developed more recently, provide promising alternatives for the production of C-Mg composites. In the present work, Mg-Al-Zn alloys have been reinforced with carbon fibers using squeeze casting and friction stir processing. The microstructures and mechanical behaviour of composites produced by both processes have then been characterised and compared to those of non-reinforced samples, with a particular attention to the damage mechanisms prevailing in the composite materials. As a result, both processes have been compared in terms of the properties of their final products and hence their ability to produce sound composites.Projet Winnomat CMg-MM