Friction stir processing of Al₃Ni intermetallic particulate reinforced cast aluminum matrix composites: Microstructure and tensile properties

Friction stir processing (FSP) is used as a secondary processing technique that has been employed to enhance the microstructure and other attributes of aluminum matrix composites (AMCs). AA6061/(0-15 wt.%) Al₃Ni AMCs were created using pure nickel powder, which was added to molten aluminum. The composite was then subjected to FSP. The AMC microstructures were studied prior to and after FSP using TEM, SEM, OM, and EBSD. The cast composite showed coarse grains, segregation, pores, aggression, as well as polygonal-shaped particles. FSP made the particle distribution homogeneous. Additionally, the coarse Al₃Ni particles were broken down into fine particles, and the process eliminated casting defects, for example pores. The size of the grain was significantly reduced because of the severe deformation of plastic and a pinning effect induced by the particles, which were reinforced. FSP also considerably increased the density of dislocations. The resulting microstructural changes improved ductility and tensile strength.