Aluminium based nanocomposites: Metal Matrix Nanocomposites

The phase evolution characteristics in the elemental blends of Al92Mn6Ce2, Al94.5Cr3Co1.5Ce1, Al87Y10Ni3 and Al88Ni9Ce2Fe1 compositions during mechanical alloying were studied. It was revealed that a wide variation of lattice parameter of Al-rich solid solutions in presence of similar level of surface and strain energy played a pivotal role in the amorphous phase formation by mechanical alloying. None of the aforesaid alloys resulted in a completely amorphous structure and hence, an attempt was made to consolidate the mechanically alloyed fully amorphous powder of Al88Ni6Ti6 composition to produce bulk Al-rich nanocomposites having densities near to the theoretical density. Consolidation was carried out by spark plasma sintering, hot pressing and conventional pressure-less sintering methods. The microstructural features and mechanical properties were also investigated for the ultrasonically cast nanocomposites of Al reinforced with nano-sized Al2O3 (average size ~10 nm) particles. Orowan mechanism predicted much higher yield strength than that observed in the present nanocomposites.