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The present paper is focused on fabrication, characterization, and aging behavior of nanostructured Al6061 alloy prepared by mechanical milling. The milling was performed on Al6061 in a planetary ball mill under argon atmosphere for various times up to 30 h. Isothermal heat treatment was then carried out on 30 h milled powder at different temperatures up to 550^°C. The structural evolution of milled and annealed powders was studied by X-ray diffraction, SEM observation, and hardness measurements. The results showed that the final milled product was an Al–Mg–Si supersaturated solid solution having a grain size of 35 nm and a microhardness of 157 HV. Additionally, Mg₂Si precipitation between 250 and 300^°C led to an increase in hardness with the peak-aging hardness value of 207 HV after heat treatment at 300^°C for 2 h. Above this temperature, due to the dissolution of the precipitates and grain growth, the hardness values decreased to 130 HV after heat treatment at 550^°C for 3 h.

Al₂O₃ coatings were prepared on T6-tempered Al6061 alloys substrate under a hybrid voltage (AC 200 V–60 Hz and DC 260 V value) by plasma electrolytic oxidation (PEO) in 30 min. The effects of different electrolytes on the abrasive behaviors of the coatings were studied by conducting dry ball-on-disk wear tests. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the coating microstructure. XRD analysis results show that the coatings mainly consist of α- and γ-Al₂O₃, and some mullite and AlPO₄ phase in Na₂SiO₃ and Na₃PO₄ containing electrolytes, respectively. The wear test results show that the coatings which were PEO-treated in Na₃PO₄ containing electrolyte presented the most excellent abrasive resistance property.

The oxide coatings were prepared on T6-tempered A16061 alloys substrate under a hybrid voltage (AC 200V-60Hz & DC 260V value) in an aluminate electrolyte by plasma electrolytic oxidation (PEO) in 5, 10, 15, 20 and 30 min, respectively. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the coating microstructure. XRD analysis results show that the coatings consist of α- and γ-Al₂O₃. The abrasive behaviors of the oxide coatings in different PEO-treated times were tested assessed by conducting dry ball-on-disk wear tests. The abrasive weight loss increased when the PEO-treated time increased, and finally became equilibrium.

Al₂O₃ coatings were prepared on Al6061 alloy substrate under a hybrid voltage by plasma electrolytic oxidation in a silicate electrolyte. Potentiodynamic polarizations tests had been carried out in 3.5wt% (0.6M) NaCl water solutions under static conditions to evaluate the corrosion performance of the coated or uncoated samples. A double-layer Al₂O₃ coating consisted of γ- and α-Al₂O₃, formed upon the Al alloy substrate. It is shown that the Al₂O₃ coatings on Al6061 alloy play roles of anticorrosive coatings, and proper treating time is suitable to enhance the corrosion resistance of the Al₂O₃ coatings.