Mechanical activation-assisted solid-state combustion synthesis of in situ aluminum matrix hybrid (Al3Ni/Al2O3) nanocomposites

Aluminum-based metal matrix composites reinforced with in situ Al3Ni and Al2O3 hybrid reinforcements are prepared by the mechanically activated, self propagating, high temperature synthesis (MASHS). The composites are fabricated from the powder blends consisting of aluminum and nickel oxide with different amounts of excess aluminum following the reaction scheme (2 + X)Al + 3NiO → XAl + Al2O3 + 3Ni (where X = 0, 5, 10 and 15 moles). The onset temperature for the displacement reaction is brought down below the melting temperature of the mechanically activated powder blends by a high energy ball milling (HEBM). The solid-state displacement reaction can effectively preserve the nanostructure of the matrix with ultra fine reinforcements formed by the in situ reaction. It is demonstrated that the composite properties can be tailored by altering the stoichiometry of reactants.