Low cost metal matrix composites based on aluminum, magnesium and copper reinforced with fly ash prepared using friction stir processing

Fly ash (FA) is a cheaper reinforcement which will bring down the production cost of metal matrix composites (MMCs). This paper reports FA reinforced MMCs based on aluminum alloy AA6061, magnesium alloy AZ31 and copper. The composites were synthesized using the novel and latest method friction stir processing (FSP). The microstructure was examined using optical microscopy, scanning electron microscopy (SEM) and electron back scattered diffraction (EBSD). A homogenous distribution of FA particles was observed in all the composites. The severe plastic deformation of the process caused fracture of FA particles. The grains were refined remarkably in the composites due to dynamic recrystallization and pinning effect. The reinforcement of FA particles enhanced the microhardness of the composites. The strengthening mechanisms were discussed.