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1. Deformation and cracking phenomena in cold sprayed 6061 Al alloy powders with nanoscale aluminum oxide films

   https://doi.org/10.1016/j.msea.2022.143036  

   Navabi, A.; Vandadi, M.; Bond, T.; Rahneshin, V.; Obayemi, J.; Ahmed, R.; Oghenevweta, J.E.; Champagne, V.; Rahbar, N.; Soboyejo, W.O. (April 2022, Materials Science and Engineering: A)
2. Finite Element Analysis of the Effect of Porosity on the Plasticity and Damage Behavior of Mg AZ31 and Al 6061 T651 Alloys

   https://doi.org/doi.org/10.1115/IMECE2019-10672  

   Perkins, R.A.; Yang, W.-H.; Liu, Y.-C.; Chen, L.; Yenusah, C. (January 2020, ASME International Mechanical Engineering Congress and Exposition)
3. The Effects of Inoculation on the Weldability of 6061 Aluminum Processed with GMA-DED

   https://doi.org/10.29391/2025.104.017  

   KLEINDIENST, JOSEPH; KLEMM-TOOLE, JONAH; BAGSHAW, NICK; ITEN, JEREMY (March 2025, Welding Journal)

   The weldability of plain and inoculated 6061 aluminum processed with gas metal arc directed energy deposition (GMA-DED) was evaluated and compared to wrought 6061. Autogenous gas tungsten arc welds of varying heat inputs were made, and the degree of solidification cracking was evaluated. The degree of cracking in the inoculated 6061 material was lower than that of plain GMA-DED and wrought 6061. Microstructure characterization revealed that the welds on the inoculated 6061 produced fine, equiaxed grains, whereas the plain 6061 showed coarse, columnar grains. A combination of heat transfer and solidification models were employed to predict the solidification morphology of the 6061 welds, which closely matched the experimental results in all cases. A model was developed to understand the effect of grain morphology on solidification cracking, and it was found that equiaxed grains shifted the critical liquid film range for cracking to lower solid fractions where thermal stresses are the lowest. However, cracking can be caused if sufficient external stresses are applied when the critical liquid film thickness is present during solidification of the equiaxed grain structure. This work provides insight into the role grain size and morphology control can have in suppressing solidification cracking of other aluminum alloys. 

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4. Effect of Nanocarbon on the Structural and Mechanical Properties of 6061 Aluminum Composites by Powder Metallurgy

   https://doi.org/10.3390/nano13222917  

   Rativa-Parada, Wilson; Sirikumara, Hansika I.; Karunanithy, Robinson; Sivakumar, Poopalasingam; Jayasekera, Thushari; Nilufar, Sabrina (November 2023, Nanomaterials)

   6061 aluminum composites with 0.5 and 1 vol. % graphene nanoplatelets as well as 1 and 2 vol. % activated nanocarbon were manufactured by a powder metallurgy method. Scanning electron microscopy and Raman spectroscopy were used to study the morphology, structure, and distribution of nanocarbon reinforcements in the composite samples. Density Functional Theory (DFT) calculations were performed to understand the aluminum-carbon bonding and the effects of hybridized networks of carbon atoms on nanocarbon aluminum matrix composites. Scanning electron microscopy showed the good distribution and low agglomeration tendencies of nanoparticles in the composites. The formation of secondary phases at the materials interface was not detected in the hot-pressed composites. Raman spectroscopy showed structural changes in the reinforced composites after the manufacturing process. The results from Density Functional Theory calculations suggest that it is thermodynamically possible to form carbon rings in the aluminum matrix, which may be responsible for the improved mechanical strength. Our results also suggest that these carbon networks are graphene-like, which also agrees with the Raman spectroscopy data. Micro-Vickers hardness and compressive tests were used to determine the mechanical properties of the samples. Composites presented enhanced hardness, yield and ultimate strength compared to the 6061 aluminum alloy with no nanocarbon reinforcement. Ductility was also affected, as shown by the reduction in elongation and by the number of dimples in the fractured surfaces of the materials. 

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5. Modeling Solidification Microstructure in an Inoculated Aluminum 6061 Alloy Processed with Gas Metal Arc Directed Energy Deposition

   https://doi.org/10.1007/s11837-024-07066-4  

   Kleindienst, Joe; Bagshaw, Nick; Iten, Jeremy; Klemm-Toole, Jonah (March 2025, JOM)

   Abstract The solidification microstructures of plain and inoculated 6061 aluminum builds manufactured with gas metal arc-directed energy deposition were studied with a combination of models and experiments. Electron back-scatter diffraction (EBSD) showed that the plain 6061 build had large, columnar grains with intergranular solidification cracking, while the inoculated build had a near-equiaxed, fine grain microstructure with no solidification cracks. By combining EBSD and energy dispersive spectrometry, the inoculated build has been shown to have exhibited globular growth while the non-inoculated build displayed a dendritic microstructure. A combination of heat transfer and modified grain morphology models were employed to predict the solidification morphology of the 6061 builds, which closely matched experimental results. A modification is proposed to the criterion marking the transition from globular to dendritic growth that better matches experimental results in this work. The results of this study are expected to provide improved methods to predict solidification microstructure for the development of new materials and processing parameters for additive manufacturing. 

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