Picture: Massachusetts Institute of Technology
Researchers at the Massachusetts Institute of Technology have developed an aluminum alloy that can be additively manufactured and achieves mechanical properties exceeding those of conventionally produced aluminum materials. The approach combines simulation-driven materials development with machine-learning methods, addressing a central challenge in metal 3D printing: the targeted control of microstructure.
At the heart of the work is an alloy composition that forms a fine distribution of nanoscale precipitates during the laser powder bed process. These so-called precipitates are crucial to the strength of aluminum. While traditional casting processes tend to promote coarse structures due to slow cooling, the rapid solidification inherent to additive manufacturing results in a much denser arrangement. Mechanical tests show that the printed samples achieve strengths approximately five times higher than cast aluminum of the same composition.
The selection of alloying elements was not carried out through broad experimental trial series, but with the help of a machine-learning model. This reduced the theoretical search space from more than one million possible combinations to just a few dozen candidates.
“If we can use lighter, high-strength material, this would save a considerable amount of energy for the transportation industry,” says Mohadeseh Taheri-Mousavi, who led the research as a postdoc at MIT and is now an assistant professor at Carnegie Mellon University.John Hart, the Class of 1922 Professor and head of MIT’s Department of Mechanical Engineering, says the benefits extend well beyond aviation. “Because 3D printing can produce complex geometries, save material, and enable unique designs, we see this printable alloy as something that could also be used in advanced vacuum pumps, high-end automobiles, and cooling devices for data centers.”
“At some point, there are a lot of things that contribute nonlinearly to a material’s properties, and you are lost,” Taheri-Mousavi says. “With machine-learning tools, they can point you to where you need to focus, and tell you for example, these two elements are controlling this feature. It lets you explore the design space more efficiently.”
The samples were printed using the Laser Powder Bed Fusion process, in which aluminum powder is melted layer by layer. The resulting microstructure remained stable even at temperatures of up to 400 degrees Celsius, significantly expanding the range of applications.
“Sometimes we have to think about how to get a material to be compatible with 3D printing,” says Hart. “Here, 3D printing opens a new door because of the unique characteristics of the process — particularly, the fast cooling rate. Very rapid freezing of the alloy after it’s melted by the laser creates this special set of properties.”“Our methodology opens new doors for anyone who wants to do 3D printing alloy design,” Taheri-Mousavi says. “My dream is that one day, passengers looking out their airplane window will see fan blades of engines made from our aluminum alloys.”
The results were published in the scientific journal Advanced Materials. In addition to MIT and Carnegie Mellon, partners from Paderborn University were involved. The researchers see their methodology as a foundation for developing additional alloys specifically tailored for 3D printing in the future.
