Influenza della temperatura sui processi di deformazione plastica a caldo di un composito a matrice di alluminio

For the last years, technological processes to manufacture parts, made by metal matrix composites (MMC) reinforced with alumina or carbide particles, have been using hot plastic deformation (like extrusion) to form them into near-net-shapes, aiming to decrease expensive secondary machining operations. In fact, as high percentage of reinforcement, characterized by high hardness and strength, brings a decreasing in machinability, making costs of products grow up, its strengthen allows to improve mechanical behaviour of composites. On the other hand, fundamental is a good physical-chemical link at matrix/reinforcement interface to obtain safe microstructure both at the end of the process productive cycles and during component underloading service. Concurrent presence of these two so different phases (in terms of deformation topics) is responsible for microstructure damaging (particle fracturing, matrix-particle interface debonding, clustering of reinforcement particles), and, therefore, cause for decreasing in mechanical properties. For this reason, a proper selection of process parameters has to be suggested to optimise the final component behaviour. In particular, regarding hot deformation technologies, in the present paper, the aluminum matrix composite Al 2124/26% vol. SiCp has been characterized in terms of microstructure and fracture mechanics behaviour, both in form of as received sintered billet, and in form of part forged into a pump body for automotive applications.