Additive Friction Stir Deposition of Aluminum Alloys and Functionally Graded Structures

State-of-the-art additive manufacturing technologies for metal parts have evolved around powder metallurgy and fusion welding-based processes. Both of these processing methodologies yield parts with inferior mechanical and physical properties as compared to wrought metal of the same composition. Additionally, the production rates for even the fastest processes are relatively low (~40 lbs/hr for Ti) and the part envelopes are limited to a few cubic feet. Aeroprobe proposes a highly scalable process for additive manufacturing of wrought metal structures based on their additive friction stir (AFS) process which provides high-strength coatings and welds (strengths comparable to the base metal UTS) while retaining a wrought microstructure. AFS has successfully deposited materials ranging from light metals, such as Al and Mg alloys, to high-temperature metals, such as Inconel 625 and oxide dispersion strengthened steels. Initial additive manufacturing demonstrations with AFS were highly successful and produced fully dense structures with wrought mechanical properties. The overall objective of this project is to further develop AFS technology into an additive manufacturing process to enable full-density, near net-shape fabrication of airframe structures. An initial process-structure-property relationship study will be conducted to demonstrate the physical and mechanical properties achievable in Al alloys via AFS. Finally, Aeroprobe will demonstrate the feasibility of AFS to produce complex 3D structures by fabricating an aluminum demonstration part of a relevant geometry.