Production of aluminium matrix composite components using conventional PM technology

The machining difficulties and processing costs related to particle reinforced aluminium matrix composites have limited the application range of these advanced materials. The present investigation deals with the production of net shape SiC particle reinforced AA6061 aluminium alloy components by a conventional powder metallurgical processing technique, involving the uniaxial cold pressing and sintering of composite powders. Three aluminium alloy powder sizes were combined with three SiC particle sizes in various volume fractions of up to 20% SiC, and processed to produce net shape tensile test samples. The tensile test results and the morphological analysis of the fracture surfaces show that this process may be used to produce well sintered, small-to-medium sized net shape aluminium composite components exhibiting ultimate tensile strength (UTS) of up to 324 MPa. The successful production of these aluminium powder based components is affected strongly by the aluminium powder size, SiC volume fraction and the SiC particle size. It is also linked to the penetration of the aluminium powder oxide layer by the hard SiC particles, which occurs during cold compaction. Based on the present investigations, a number of processing improvements are suggested, which should further advance the usefulness of this technically uncomplicated net shape processing method for the production of aluminium matrix composites.