Effect of initial grain size on microstructure and mechanical properties of in situ hybrid aluminium nanocomposites fabricated by friction stir processing

Azimiroeen, Ghasem and Kashani-Bozorg, Seyed Farshid and Nosko, Martin and Lotfian, Saeid (2023) Effect of initial grain size on microstructure and mechanical properties of in situ hybrid aluminium nanocomposites fabricated by friction stir processing. Applied Sciences, 13 (12). 7337. ISSN 2076-3417 (https://doi.org/10.3390/app13127337)

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Abstract

Friction stir processing (FSP) offers a unique opportunity to tailor the microstructure and improve the mechanical properties due to the combination of extensive strains, high temperatures, and high-strain rates inherent to the process. Reactive friction stir processing was carried out in order to produce in situ Al/(Al13Fe4 + Al2O3) hybrid nanocomposites on wrought/as-annealed (673 K) AA1050 substrate. The active mixture of pre-ball milled Fe2O3 + Al powder was introduced into the stir zone by pre-placing it on the substrate. Microstructural characterisation showed that the Al13Fe4 and Al2O3 formed as the reaction products in a matrix of the dynamically restored aluminium matrix. The aluminium matrix means grain size was found to decrease markedly to 3.4 and 2 μm from ~55 μm and 40–50 μm after FSP using wrought and as-annealed substrates employing electron backscattered diffraction detectors, respectively. In addition, tensile testing results were indicative that the fabricated surface nanocomposite on the as-annealed substrate offered a greater ultimate tensile strength (~160 MPa) and hardness (73 HV) than those (146 MPa, and 60 HV) of the nanocomposite formed on the wrought substrate.

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