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

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 elongation were increased from 93±5 MPa and 13·8 to 117±3 MPa and 25·3 after employing four-pass FSP. Fractographic studies also revealed that agglomerated TiO2 particles could operate as sites of crack initiation and propagation, which led to brittle fracture. By increasing the number of FSP passes, the agglomerates were disappeared and the ductility was enhanced remarkably.

Micro-hardness and wear behavior of AA2014/Al2O3 surface composite produced by friction stir processing

“…The average grain size was reduced from ~ 21.9 µm in base material to ~ 9.2 µm in 1000 rpm sample and further ~ 3.8 µm in 1400 rpm sample, which clearly states that with the increase in the tool rotating speed, the average grain size of the sample reduces. In some studies [38][39][40], clustering and agglomeration were found during the processing, but no major clustering or agglomeration was observed during the present investigation.…”

Effects of nanometric inclusions on the microstructural characteristics and strengthening of a friction-stir processed aluminum–magnesium alloy

“…Four FSP passes were applied to distribute the nanoparticles in the aluminum matrix. The effect of FSP pass number on the homogeneity distribution of pre-inserted ceramic nanoparticles has been reported in recent publication of the authors [52]. It has been found that employing four-pass FSP with 100% overlap without changing the rotational/traveling direction is enough to attain a uniform distribution of the nanoparticles in the matrix.…”

Effect of Nano-TiO$_2$ Particles on Wear and Corrosion Behaviour of AA6063 Surface Composite Fabricated by Friction Stir Processing

“…Lakshmanan et al [13] studied about the performance characteristics of AA6061/nano-B 4 C metal matrix nanocomposites by using ultrasonic cavitation assisted casting process and observed that wear resistance of aluminium alloy-nano-boron carbide composites compared to the monolithic alloy very much improved. Khodabakhshi et al [14] fabricated the Al-Mg nanocomposites by incorporating TiO 2 particles and found that solid-state chemical reaction between TiO 2 nanoparticles and the Al-Mg matrix led to in situ formation of Al 3 Ti and MgO nanoparticles.…”