Microstructure and mechanical properties of an Al-Ni-Co intermetallics reinforced Al matrix composite

A new intermetallic particle reinforced metal matrix composite was produced from pure Al and 15 wt% Al(72)Ni(12)Co(16) quasicrystalline particles by stir-casting method, followed by hot-extrusion. Microstructural analysis of the as-cast composite shows that the Al(72)Ni(12)Co(16) quasicrystalline phase has transformed to the crystalline phase Al(9)(Co, Ni)(2) and an eutectic structure has formed in the Al matrix during the casting process. The particle size of the Al(9)(Co, Ni)(2) phase is much smaller than that of the original quasicrystalline particles. After extrusion, the composite has a more uniform distribution of the reinforcement particles and eutectic structure as well as a reduced porosity. Tensile tests indicate that the mechanical properties of the as-cast composite are improved over the matrix properties remarkably, except for the ductility. The strength and ductility of the composite can be improved by the hot-extrusion, while the elastic modulus can be slightly decreased.