42. Analysis of Interfaces in AA7075/ Recycled WC Particles Composites Produced via Liquid Route

Casting of composites is a simple and low cost route to produce composites, which allows numerous possibilities in terms of reinforcement location in the cast part and high geometry flexibility of the products. However, interfaces between reinforcement and metal depend on the behaviour of the particles in liquid metal during processing. The work investigates the effects of parameters such as temperature and time of contact between WC particles and liquid aluminium, and reinforcement content, in the production of cast AA7075/WC composites. WC particles coming from recycled cutting tools are used as reinforcement for aluminium alloys AA 7075, widely used in aeronautical domain. Reinforcement contents of 15 and 30 wt %, temperatures of 700, 740 and 780C, and contact time of 1, 2, 3 and 4 h were the values of the investigated variables. Microstructure of cast composites produced under these conditions were analysed by OM, SEM and EDS microanalysis. A reaction layer was found in the interface between metal and WC, with composition and micro constituents depending on the studied parameters. A mechanism of formation of the reaction layer is proposed.