Researchers at Tohoku University’s Institute for Materials Research and New Industry Creation Hatchery Center have made a groundbreaking advancement in multi-material 3D printing, creating a durable steel-aluminum alloy that could revolutionize the production of lightweight and robust automobile components.

Metal 3D printing involves building objects layer by layer, where metal powders are fused using heat from a laser. This technique provides remarkable precision, enabling the production of intricate, highly customizable designs with minimal material waste compared to traditional manufacturing. One of the standout benefits of 3D printing is its ability to produce “multi-material structures.” These components combine different metals to optimize performance—such as pairing aluminum with steel to create lightweight parts that retain strength. This feature has made advanced 3D printing a highly promising technology for automotive manufacturing and other industries.

However, multi-material 3D printing comes with its challenges. “A key issue in additive manufacturing is the formation of brittle intermetallic compounds at the interfaces between different metals, such as steel and aluminum,” explains Associate Professor Kenta Yamanaka of Tohoku University. “While this makes the material lighter, it can also cause brittleness, which compromises its strength.”

To address this issue, the research team sought to create a steel-aluminum alloy that was both lightweight and durable. They used Laser Powder Bed Fusion (L-PBF), a cutting-edge metal 3D printing technology that uses a laser to melt metal powders selectively. The team found that increasing the laser scan speed significantly reduced the formation of brittle intermetallic compounds like Al5Fe2 and Al13Fe4. They discovered that this higher scan speed promoted non-equilibrium solidification, which minimized solute partitioning and created strong bonding interfaces.

“Achieving this required a deep understanding of the in-situ alloying mechanism,” says Specially Appointed Assistant Professor Seungkyun Yim, also from Tohoku University. “You can’t just merge two metals without understanding how they interact at the interface.”

With this breakthrough, the team successfully produced the world’s first full-scale automotive multi-material component—a suspension tower—with customized geometry. The research group’s next goal is to apply their findings to improve the bonding of other metal combinations, broadening the potential applications of this innovative approach.

This development paves the way for creating lightweight, durable automotive components using 3D printing, offering substantial advantages in terms of material efficiency, performance, and design flexibility.

By Impact Lab