David Florián-Algarín

New and innovative technologies have expanded the quality and applications of aluminum welding in the maritime, aerospace, and automotive industries. One such technology is the addition of nanoparticles to aluminum matrices, resulting in improved strength, operating temperature, and stiffness. Furthermore, researchers continue to assess pertinent factors that improve the microstructure and mechanical characteristics of aluminum welding by enabling the optimization of the manufacturing process. Hence, this research explores alternatives, namely cost-effective aluminum welding fillers reinforced with niobium diboride nanoparticles. The goal has been to improve weld quality by employing multi-objective optimization, attained through a central composite design with a response surface model. The model considered three factors: the amount (weight percent) of nanoparticles, melt stirring speed, and melt stirring time. Filler hardness and porosity percentage served as response variables. The optimal parameters for manufacturing this novel filler for the processing conditions studied are 2% nanoparticles present in a melt stirred at 750 rpm for 35.2 s. The resulting filler possessed a 687.4 MPA Brinell hardness and low porosity, i.e., 3.9%. Overall, the results prove that the proposed experimental design successfully identified the optimal processing factors for manufacturing novel nanoparticle-reinforced fillers with improved mechanical properties for potential innovative applications across diverse industries.

The Portevin-Le Chatelier (PLC) phenomenon or dynamic strain aging in Al–0.5 wt. % Mg alloys was investigated at different strain rates. This research also examined the effect of γAl₂O₃ nanoparticles on the PLC phenomenon. A nanocomposite made of A206/1.0 wt. % γAl₂O₃ was manufactured to this purpose and then, added to an Al–0.5 wt. % Mg melt to obtain ingots of Al–0.5 wt. % Mg–20 wt. % A206/1.0 wt. % γAl₂O₃ and Al–0.5 wt. % Mg–10 wt. % A206/1.0 wt. % γAl₂O₃ with 6 mm diameter. Cold deformation allowed manufacturing 1 mm diameter wires using the 6 mm diameter ingots. A 300 °C solution treatment, followed by rapid cooling in ice water permitted to retain Mg atoms in solid solution. The tensile tests performed on the wires revealed the PLC phenomenon upon the tensile stress vs. strain plastic zone. The phenomenon was quantified using MatLab™ and statistical analysis. The results demonstrated how the alumina nanoparticles can diminish the serration amplitude of the PLC phenomenon.

In Al-Mg alloys, the Portevin-Le Chatelier phenomenon, or dynamic strain aging, reveals itself as serrations upon plastic tensile deformation. This research evaluates this phenomenon when Al/NbB₂ nanocomposite pellets are added to a magnesium-supersaturated Al matrix. A ball-milled 90 wt % Al and 10 wt % NbB₂ nanocomposite helped inoculate an Al-Mg melt to incorporate the nanoparticles effectively. The melt was cast into rods that were cold-rolled into 1 mm diameter wires. Two sets were prepared: The first group was an as-cast set of samples, for comparison purposes, whereas the second was a solution-treated set. The solution treatment consisted of annealing followed by ice-water quenching. The results corroborating that the phenomenon was observable only in the specimens bearing the solution treatment, were used as the research baseline. Said treated alloy was compared to one containing the nanoparticles, which proved that the NbB₂ particles caused a reduction of the serrated signal amplitude.

This research focuses on the fabrication of aluminum wires treated with MoB₂ nanoparticles and their effect on selected mechanical and thermal properties of the wires. These nanoparticles were obtained by fragmentation in a high-energy ball mill and then mechanically alloyed with pure aluminum powder to form Al/MoB₂ pellets. The pellets were added to molten pure aluminum (99.5%) at 760 °C. Afterwards, the treated melt was cast into cylindrical ingots, which were cold-formed to the desired final diameter with intermediate annealing. X-ray diffraction and optical microscopy allowed characterizing the structure and microstructure of the material. The wires underwent tensile and bending tests, as well as electrical measurements. Finally, this research demonstrated how the mechanical properties of aluminum wires can be enhanced with the addition of MoB₂ nanoparticles with minimal effects on the material resistivity.

This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl₂O₃ nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl₂O₃ nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al–γAl₂O₃ nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires’ electrical conductivity compared with that of pure aluminum and aluminum–copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding.

This study focuses on the fabrication of aluminum treated with nanocomposites made of aluminum and NbB2 and ZrB2 nanoparticles. These nanoparticles were obtained by fragmentation in a ball mill and then mechanically alloyed with pure aluminum powder to form Al/NbB2 and Al/ZrB2 nanocomposite pellets, which were then sintered at 260°C for half an hour to improve the metal/borides interface. The sintered nanocomposites were incorporated into molten pure aluminum to produce 1-mm-diameter wires after cold forming. The wire specimens were mechanically characterized and their electrical resistivity was measured. Our results demonstrated the feasibility of improving the mechanical properties of aluminum wires with the addition of nanocomposites without significantly affecting their electrical conductivity.

This study hinges on the feasibility of strengthening Al and Al-Mg wires by adding Al nanocomposite pellets containing MgB ₂ nanoparticles into the melt upon fabrication. These MgB ₂ nanoparticles were obtained by fragmentation using a high-energy ball mill, and were, afterward, mechanically alloyed with pure aluminum. The resulting MgB ₂ /Al nanocomposite pellets were sintered at 260°C to be subsequently added into molten aluminum and an Al-Mg alloy melt. Cold rolling intercalated with stepwise annealing allowed the fabrication of 1 mm diameter wires with a final area reduction of 96%. Mechanical and physical properties of the treated wire specimens were compared to those of similarly processed pure aluminum wire. The ultimate tensile strength of the treated wires increased approximately double fold with respect to untreated wires at the expense of some loss in electrical conductivity.

This study focuses on the fabrication of aluminum treated with nanocomposites made of aluminum and NbB ₂ and ZrB ₂ nanoparticles. These nanoparticles were obtained by fragmentation in a ball mill and then mechanically alloyed with pure aluminum powder to form Al/NbB ₂ and Al/ZrB ₂ nanocomposite pellets, which were then sintered at 260°C for half an hour to improve the metal/borides interface. The sintered nanocomposites were incorporated into molten pure aluminum to produce 1-mm-diameter wires after cold forming. The wire specimens were mechanically characterized and their electrical resistivity was measured. Our results demonstrated the feasibility of improving the mechanical properties of aluminum wires with the addition of nanocomposites without significantly affecting their electrical conductivity.