Mechanical and Microstructural Characterization of Hybrid Aluminum Nanocomposites Synthesized from an Al–Fe₃O₄ System by Friction Stir Processing

Reactive friction stir processing was used to fabricate in situ hybrid nano-composite. Nano-sized Al₂O₃ and Al₁₃Fe₄ products were formed in the stir zone of rolled AA1050 through the addition of pre-milled Al + Fe₃O₄ powder mixture. The thermomechanical phenomena associated with the process and addition of active powder mixture provided the occurrence of the aluminothermy reaction. Microstructural investigations showed significant matrix grain refinement; the mean grain size of ~ 3 μm was achieved. The nano-sized reinforcement products prevented grain growth after dynamic recrystallization process by pinning the grain boundaries. The excellent matrix grain refining and formation of in situ hard reinforcements led to the increase of hardness and tensile strength to ~ 56% and 49% over those of the untreated substrate, respectively.