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The strength and wear resistance of aluminium alloys must be improved to enhance their usage in lightweight constructions. Thus, in this study, graphene nanoplates (GNPs) and boron nitride (BN) nanoparticles were reinforced into the Al 5251 aluminium alloy by friction stir processing (FSP). The Al 5251 aluminum alloy sheets were patterned with holes and filled by mono GNPs, mono BN nanoparticles and a hybrid of BN nanoparticles and GNPs. The microstructure, wear, and mechanical properties of the as-received, after FSP, and the manufactured surface nanocomposites were analysed. Wear tests were performed using two methods: weight loss and volume loss methods. FSP led to four times grain refinement. Due to the Zener pinning effect, the reinforcement nanoparticles improved the grain refinement effect by seven times decrease in the mean grain size. The wear rate by volume and weight loss with reinforcing BN nanoparticles decreased by 160 and 1,340%, respectively. Note that the GNP reinforcement insignificantly improved the wear resistance and hardness compared with the BN nanoparticles. The hardness was increased by 50, 120, and 80% by reinforcing the Al 5251 alloy with GNPs, BN, and a hybrid of BN nanoparticles and GNPs, respectively. The nanocomposite reinforced with GNPs exhibited superior mechanical properties compared to the other nanocomposites.

This paper investigates the effects of Friction Stir Processing (FSP) parameters on the microstructure and mechanical properties of an Al-Si7Mg0.2 alloy. The study's findings indicate that augmenting the rotational velocity of the tool in the context of Friction Stir Processing can reduce grain size and enhance the alloy's mechanical properties. The optimization of process temperature plays a vital role in managing the thermal profile and preventing undesirable consequences such as overheating or excessive cooling. These adverse effects can significantly impact the microstructure and properties of the alloy. The finer grain size of the FSPed samples resulted from the intense plastic deformation and dynamic recrystallization during the process. This grain refinement improved hardness, wear, and corrosion resistance. The temperature distribution during FSP using finite element simulation was highly dependent on the process parameters, such as the rotational speed and the dwell time. The results of this study are employed to develop a fitting model to predict the temperature distribution along the workpiece during the dwelling stage, which can be used to optimize the process parameters for different applications. The optimization of the heat generation inside the stirred zone plays a vital role in managing the thermal profile and preventing undesirable consequences such as overheating or excessive cooling. These adverse effects can significantly impact the microstructure and properties of the alloy. [ABSTRACT FROM AUTHOR]

This work studies the effect of incorporating a mix of reinforcement particles of a hard and soft nature on the microstructure and mechanical and physical properties of a high-strength aluminum alloy, AA7075. A friction stir processing technique was used for compositing the surface of this alloy. The vanadium carbide (VC) was selected to be the hard reinforcement, while the boron nitride (BN) and graphene nanoplates (GNPs) were chosen as soft reinforcements. Mono VC, hybrid reinforcements combined of 50 vol.% VC and 50 vol.% BN, and triple reinforcements combined of 33.4 vol.% VC, 33.3 vol.% BN, and 33.3 vol.% GNPs were used for producing the composites. Intensive grain refinement was observed, 930%, in the composite with triple reinforcements. The microhardness and the ultimate compressive strength were improved and reached b0, 29%, respectively, in composites that contained GNPs. The thermal properties were significantly improved, and the coefficients of thermal expansion (CTE) and thermal conductivity decreased to 88% and 15%, respectively. The composite's electrical conductivity was decreased by 58% with triple reinforcements. [ABSTRACT FROM AUTHOR]

In the present work, an advanced technique was applied to coat an Al 2024 alloy with a surface composite layer reinforced with various nanoparticles. The surface of Al 2024 aluminum alloy was modified with Ta2C, Al2O3 and multi wall carbon nanotubes MWCNTs nanoparticles by friction stir process (FSP). An improvement in the surface of the fabricated nanocomposite due to the refinement of the microstructure grains was achieved. In addition, a significant improvement in the hardness and wear behavior was observed. The reinforcement particles were incorporated into double and triple hybrid composite particles to determine the most effective combination for the controlled properties. The results showed that for the composite reinforced with a double hybrid of Al2O3 and MWCNTs, the microstructure grains of the fabricated nanocomposite surface were refined by 40 times. The hardness was significantly improved, i.e., it was increased by 48% by incorporating the triple reinforcement (Ta2C, Al2O3, and MWCNTs) into the surface of Al 2024 aluminum alloy. The results of wear properties were in agreement with the results of hardness; the maximum wear resistance was obtained for Al 2024-Ta2C + Al2O3 + MWCNTs, and the wear rate was reduced by 11 times. [ABSTRACT FROM AUTHOR]

The effect of isothermal multidirectional forging (IMF) on the microstructure evolution of a conventional Al–Mg-based alloy was studied in the strain range of 1.5 to 6.0, and in the temperature range of 200 to 500 °C. A mean grain size in the near-surface layer decreased with increasing cumulative strain after IMF at 400 °C and 500 °C; the grain structure was inhomogeneous, and consisted of coarse and fine recrystallized grains. There was no evidence of recrystallization when the micro-shear bands were observed after IMF at 200 and 300 °C. Thermomechanical treatment, including IMF followed by 50% cold rolling and annealing at 450 °C for 30 min, produced a homogeneous equiaxed grain structure with a mean grain size of 5 µm. As a result, the fine-grained sheets exhibited a yield strength and an elongation to failure 30% higher than that of the sheets processed with simple thermomechanical treatment. The IMF technique can be successfully used to produce fine-grained materials with improved mechanical properties. [ABSTRACT FROM AUTHOR]

This paper presents the effect of temperature and strain rate on the superplastic deformation behavior of Ti-3%Mo-1%V-4%Al, Ti-4%V-6%Al, and Ti-1.8%Mn-2.5%Al alloys, which have different initial microstructures. The microstructure, before and after superplastic deformation in the deformation regimes that provided the maximum elongation, was analyzed. The deformation regimes, corresponding to the minimum strain hardening/softening effect, provided a higher elongation to failure due to their low tendency toward dynamic grain growth. As the values of stress became steady (σs), the elongation to failure and strain-hardening coefficient were analyzed under various temperature–strain rate deformation regimes. The analysis of variance of these values was performed to determine the most influential control parameter. The results showed that the strain rate was a more significant parameter than the temperature, with respect to the σs, for the investigated alloys. The most influential parameter, with both the elongation to failure and strain-hardening coefficient, was the temperature of the Ti-3%Mo-1%V-4%Al and Ti-1.8%Mn-2.5%Al alloys and the strain rate of the Ti-4%V-6%Al alloy. [ABSTRACT FROM AUTHOR]