Al-Mn-Fe-Si alloys, often designated as 3xxx series Al alloys, are used to manufacture beverage cans and heat exchangers in energy and automotive systems, which requires the high demand for recyclability to reduce the energy and carbon emissions. The compositions of recycled alloys from scrap often fall outside commercial product specifications, leading to their downcycling as their properties mostly remain unknown. The thesis establishes the technical basis of a data-driven approach to accelerate the development of recyclable Al-Mn-Fe-Si sheet alloy, involving combinatorial alloy synthesis by laser direct energy deposition (DED) additive manufacturing (AM), small-scale rolling, small-scale mechanical testing, and thermodynamic calculation. The study mainly focuses on developing quantitative understandings of the composition-process-microstructure-property relationships. The study discovers new insights for phase transformation as the function of alloy composition and processing condition and outlines its roles for recrystallization and mechanical properties.

 

This work first develops the DED processing route using 3104 alloy and benchmarks its microstructure and mechanical properties against those of direct-chill (DC)-cast 3104. The results reveal that microstructure and phase transformation during DED is strongly influenced by the unique thermal history of the process, leading to substantial differences in constituent particle formation, dispersoid evolution, grain structure, recrystallization behavior, and tensile properties compared with DC-cast materials. These findings establish the need to tailor the DED process in order to better reproduce the microstructural characteristics relevant to wrought sheet alloy development. Based on this understanding, the study then optimizes the DED process through substrate heating and in situ grain refinement. Substrate heating is used to modify phase transformation pathways and tailor the formation of constituent particles and dispersoids, while grain refinement promotes a columnar-to-equiaxed transition in grain structure. In combination with small-scale rolling, these process modifications enable the production of DED materials with microstructural features, recrystallization behavior, and mechanical properties that more closely resemble those of DC-cast counterparts.

 

Finally, the optimized DED process is applied as a high-throughput platform to demonstrate recyclable alloy development in Al-Mn-Fe-Si systems. Case studies on revealing Fe effects on ductility show that the approach can rapidly screen unexplored alloy compositions and efficiently assess their phase transformation, recrystallization response, and mechanical performance. This work demonstrates that high-throughput laser DED can serve as an effective experimental platform for accelerating the development of recyclable Al-Mn-Fe-Si sheet alloys