Nickel particle embedded aluminium matrix composite with high ductility

Nickel particulate reinforced aluminium matrix composite was processed without formation of deleterious Al₃Ni intermetallic by friction stir processing (FSP). FSP resulted in uniform dispersion of nickel particles in the aluminium matrix with excellent interfacial bonding and also lead to grain refinement of the matrix. The composite exhibited a threefold increase in the yield stress (0.2% proof stress). The most novel feature of the composite is that an appreciable amount of ductility is retained while the strength increases significantly. The microstructure evolution was studied by transmission electron microscopy and electron backscattered diffraction analysis. EBSD analysis showed a dynamically recrystallized equiaxed microstructure having a considerable fraction of low-angle boundaries. TEM observations revealed that these low-angle boundaries are essentially subgrain boundaries formed by dislocation rearrangement and absorption during friction stir processing.