Microstructural and Mechanical Properties of Al-Based Composites Reinforced with In-Situ and Ex-Situ Al2O3 Nanoparticles

A powder metallurgy route based on high-energy ball milling and powder consolidation by ECAP is used to produce Al-matrix composites reinforced with Al2O3 nanoparticles. The reinforcement is produced in-situ during the milling process and added ex-situ. Ball milling led to the fragmentation of the oxide layer that covers the Al particles and to the formation of very thin Al2O3 dispersoids. Moreover, it was able to break the Al2O3 particle clusters added ex-situ and to embed the oxide in the ductile Al matrix. After powder consolidation by ECAP, the nanocomposites showed an ultra-fine grained and fully dense matrix characterized by uniformly dispersed nanoparticles.