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There are many engineering applications in which composite materials are required

to satisfy two or more criteria regarding physical and mechanical properties. In

this article, Al-matrix nanocomposites reinforced with different volume fractions

of SiC nanoparticles (~ 50 nm; up to 6%) were processed by powder metallurgy

(P/M) routes through mechanical milling and hot consolidation techniques.

Microstructural studies showed that nano-metric Al2O3 particles with a size of ~ 20 nm

and volume fraction of ~ 2% were formed and distributed in the metal matrix, owing

to the surface oxides breaking. Microstructural analysis also revealed that the size

of cellular structure and the density of dislocations increased with the concentration

of hard inclusions. However, the limit of deformability of the nanocomposite materials

containing a high amount of nanoparticles (> 4 vol%) led to less densification

upon hot consolidation stages deteriorating mechanical strength. It was shown

that the formation of non-equilibrium grain boundaries with high residual stresses

as well as scattering around nano-metric inclusions and dislocations influenced the

electrical resistivity of the nanocompsites. A linear relationship between the

concentration of hard inclusions, electrical resistivity and yield strength was found.

This observation demonstrates the importance of substructure and microstructures

on the physico-mechanical properties of metal matrix nanocomposites.
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