Excellence in Research: Understanding Dissimilar Metal Joints Formed Using Additive Friction Stir Deposition

About This Grant

This Excellence in Research (EiR) project aims to enhance the manufacturing of durable dissimilar metal joints using an advanced solid-state fabrication technique called Additive Friction Stir Deposition. Dissimilar metal joints, which combine the strengths of different metals, are essential in industries such as aerospace and automotive, where materials need to be lightweight, strong, and resistant to corrosion. However, joining metals with different properties poses significant challenges, such as the formation of brittle compounds and the development of residual stresses that can weaken the joints. Existing methods for joining dissimilar metals often struggle with these issues, leading to limitations in the quality and reliability of the resulting products. This research will tackle these challenges by systematically investigating how the additive friction stir deposition process can create robust and reliable metal joints, beginning with the study of Al6061 and Al7075 aluminum alloys. These alloys have distinct compositions and mechanical properties, which will be helpful for understanding the underlying mechanisms of dissimilar metal joining. The project will optimize processing parameters, perform detailed material characterizations, and use advanced computational modeling to understand the relationships between process, structure, and properties. The knowledge gained from this research will be applied to other metal combinations, such as aluminum/steel and aluminum/copper, potentially transforming the field of metal joining technology and expanding the use of dissimilar metal joints in demanding applications. The project’s broader impact extends to enhancing STEM education and workforce development by providing hands-on research experiences for graduate and undergraduate students, equipping them with valuable skills for careers in science and engineering. Additionally, the findings will be integrated into new courses, outreach activities, and professional development programs for community college and high school teachers, thereby enriching the educational pipeline. The potential applications of this research include benefit to industries and government agencies by enabling the development of advanced materials with improved performance, fostering a skilled workforce, and supporting the nation’s technological leadership and economic competitiveness. The project aims to develop a comprehensive understanding of the process-structure-property relationships inherent in additive friction stir deposition for Al6061/Al7075 joints, with the goal of optimizing joining strategies and extending the approach to other metal combinations. The research will address key challenges associated with joining metals of varying compositions and mechanical properties, including mitigating brittle intermetallic formation, minimizing residual stresses, and enhancing joint integrity. The approach will involve systematically optimizing additive friction stir deposition parameters such as tool rotation speed, traverse speed, feedstock feed rate, and axial force. Extensive material characterization will be conducted, including microstructure analysis using scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscatter diffraction, and transmission electron microscopy, phase identification with X-ray diffraction, mechanical testing (tensile and hardness tests), thermophysical property measurements (thermal conductivity, diffusivity, specific heat), and corrosion resistance evaluations. Post-fabrication heat treatments will be performed to enhance joint performance, and various heat treatment profiles will be assessed to determine their effects on microstructural evolution and overall joint properties. Advanced computational methods will complement the experimental work, employing thermodynamic modeling to predict phase transformations, finite element analysis to simulate stress and deformation during the additive friction stir deposition process, and machine learning algorithms to establish correlations between processing conditions, microstructure, and material properties. The anticipated outcomes include a detailed understanding of the factors influencing the quality and durability of additive friction stir deposition joints, enabling the fabrication of lightweight, durable metal structures with superior mechanical and thermal properties. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.