Consolidation behavior of mechanically alloyed aluminum based nanocomposites reinforced with nanoscale Y2O3/Al2O3 particles

The compaction, sintering, microstructural and micro hardness behavior of nanocomposite powders were examined using pre-mixed (elemental) Al6063, Al6063/1.5Al2O3 Al6063/1.5Y2O3 and Al6063/0.75Al2O3/0.75Y2O3 powders. Micro-crystalline (MC) and ultrafine-grained (UFG) Al6063 nanocomposites were prepared from elemental powders by blending (0 h) and mechanical alloying (40 h). The effects of nano-size reinforcement, milling time (0 and 40 h), sintering temperature and sintering time on the relative density and micro hardness of the consolidated nanocomposite powders were examined. The compressibility behavior of nanocomposite powders in terms of particle rearrangement and plastic deformation mechanisms were investigated using Panelli and Ambrozio Filho, modified Heckel and Ge equations. The sinterability analysis of the MC and UFG nanocomposites were carried out at varying sintering temperatures (773 to 873 K) and sintering time (60 to 180 min). XRD patterns were analyzed to find the phases present and to determine crystallite size, lattice strain and lattice parameter of the sintered composites with broadening of peaks. Microstructure analysis of UFG nanocomposites were examined to study the ceramic particle distribution and to confirm the absence of other phases using TEM, FESEM and SEM/EDS.