Microstructural and mechanical properties of Al–Mg/Al2O3 nanocomposite prepared by mechanical alloying

The effect of milling time on the microstructure and mechanical properties of Al and Al–10 wt.% Mg matrix nanocomposites reinforced with 5 wt.% Al2O3 during mechanical alloying was investigated. Steady-state situation was occurred in Al–10Mg/5Al2O3 nanocomposite after 20 h, due to solution of Mg into Al matrix, while the situation was not observed in Al/5Al2O3 nanocomposite at the same time. For the binary Al–Mg matrix, after 10 h, the predominant phase was an Al–Mg solid solution with an average crystallite size 34 nm. Up to 10 h, the lattice strain increased to about 0.4 and 0.66% for Al and Al–Mg matrix, respectively. The increasing of lattice parameter due to dissolution of Mg atom into Al lattice during milling was significant. By milling for 10 h the dramatic increase in microhardness (155 HV) for Al–Mg matrix nanocomposite was caused by grain refinement and solid solution formation. From 10 to 20 h, slower rate of increasing in microhardness may be attributed to the completion of alloying process, and dynamic and static recovery of powders.

► The presence of Mg has remarkable effects on crystallite size and lattice strain.
► The solution of Mg in the Al matrix accelerates the mechanical milling stages.
► The microhardness increased in the presence of Mg.
► The presence of Mg has significant effect on lattice parameter.
► Steady-state situation was occurred in presence of Mg.