N.A. Burgos, O.M. Suarez
University of Puerto Rico at Mayaguez,
United States
Keywords: Nanoparticle-reinforced fillers, Aluminum-magnesium alloys, Welding metallurgy, Niobium diboride (NbB₂) nanoparticles, Aerospace structural materials
Summary:
Aerospace components utilizing advanced and reliable light alloys are crucial for manufacturing lightweight, cost-effective structures for space exploration missions. Aluminum alloys, particularly AA5356, are commonly used as fillers in such applications due to their excellent corrosion resistance and weldability. However, these fillers present high fabrication costs due to the alloying elements and post-welding treatments required to achieve optimal mechanical properties. To address these challenges, incorporating niobium diboride (NbB₂) nanoparticles into aluminum-magnesium (Al-Mg) fillers has been proposed to enhance mechanical strength, service temperature resistance, and hardness compared to unreinforced fillers. In this study, we hypothesize that adding 4% magnesium, in conjunction with niobium diboride, will produce improved welds in AA6xxx-based alloys capable of withstanding the extreme conditions of space exploration. Our research focuses on developing and optimizing a novel Al-Mg-based filler reinforced with NbB₂ nanoparticles to create multifunctional aerospace structures that ensure mission safety and success. NbB₂ nanoparticles were synthesized by fragmenting bulk NbB₂ by using a high-energy ball milling process to test this hypothesis. These nanoparticles produced Al/NbB₂ nanocomposite pellets via cold welding. The pellets were subsequently introduced into molten Al-Mg alloys through stir casting, providing a simple, cost-effective, and scalable fabrication method. This method enables uniform dispersion of nanoparticles within the filler material, leading to enhanced mechanical performance and reduced defect formation during welding. Preliminary mechanical testing, including tensile tests and Vickers hardness measurements, demonstrated up to a 40% improvement in the mechanical properties of aluminum welds utilizing the nanoparticle-reinforced filler compared to unreinforced welds. Specifically, tensile strength values reached approximately 140 MPa, while hardness measurements showed an increase to 315 HV. Additionally, thermal analysis revealed a 5% increase in the melting point of the reinforced filler material (661.35°C) compared to the unreinforced counterpart, suggesting improved thermal stability under extreme conditions. These results confirm that NbB₂ nanoparticles significantly enhance the welds' strength, hardness, and reliability, rendering them more suitable for extreme aerospace environments while maintaining cost-effectiveness. The improved mechanical performance of these reinforced fillers suggests their potential for reducing material costs and increasing the longevity of critical aerospace components, making them an attractive alternative to conventional aluminum fillers. Future work includes conducting further thermal analysis to investigate the alloy's solidification behavior and assess its impact on the microstructural evolution of the welds. Additionally, electrical resistivity analysis will be performed to determine the conductivity of the reinforced material, which is crucial for applications where thermal and electrical performance must be optimized. Finally, a finite element model will be developed to simulate welding behavior and failure mechanisms, providing insights into the long-term performance and reliability of the proposed filler material in real-world aerospace conditions. This research contributes to the advancement of high-performance aerospace materials, ensuring structural integrity, enhanced durability, and improved weld quality for next-generation space exploration missions. By leveraging nanoparticle reinforcement, this study paves the way for more efficient, reliable, and cost-effective aerospace structures capable of withstanding the extreme conditions encountered in space.