Reactive friction stir processing of AA 5052–TiO2 nanocomposite: process–microstructure–mechanical characteristics

TLDR: In this article, the authors employed this process to fine-distribute TiO2 nanoparticles throughout an Al-Mg alloy, aiming to enhance mechanical properties, and the average grain size of the nanocomposite was ∼2 μm.

Abstract: Friction stir processing (FSP) is a solid state route with a capacity of preparing fine grained nanocomposites from metal sheets. In this work, we employed this process to finely distribute TiO2 nanoparticles throughout an Al–Mg alloy, aiming to enhance mechanical properties. Titanium dioxide particles (30 nm) were preplaced into grooves machined in the middle of the aluminium alloy sheet and multipass FSP was afforded. This process refined the grain structure of the aluminium alloy, distributed the hard nanoparticles in the matrix and promoted solid state chemical reactions at the interfaces of the metal/ceramic particles. Detailed optical and electron microscopic studies showed that the microstructural homogeneity was improved with repetition of FSP up to four passes. The average grain size of the nanocomposite was ∼2 μm, while nanometric MgO and Al3Ti particles were formed in situ and homogenously distributed in the metal matrix. Mechanical characterisations showed that the yield strength and e...