How to print a car: High-performance multi-material 3D printing techniques

The metal 3D printing process involves building objects by depositing metal layer by layer and using heat to bond them together. The precision of 3D printing allows for the production of unique, highly customizable shapes that often produce less wasteful by-products than traditional manufacturing methods. It is also possible to create “multi-material structures” through 3D printing, strategically combining different materials to obtain the best performance of the component. For example, steel auto parts can be made lighter by combining them with aluminum. Due to these advantages, mastering this type of 3D printing technology has attracted widespread attention from researchers.

However, the technology does face some challenges.

“Multi-materials have become a hot topic in the additive manufacturing field due to their process flexibility,” explains Associate Professor Kenta Yamanaka (Tohoku University). “However, a major challenge in practical implementation is that for certain metal combinations, such as steel and aluminum Likewise, brittle intermetallic compounds form at dissimilar metal interfaces, so although the material is now lighter, it eventually becomes more brittle.

The goal of this research is to produce a steel-aluminum alloy that is lightweight but does not compromise strength. To this end, the research team used laser powder bed fusion (L-PBF), one of the main metal 3D printing technologies, which uses lasers to selectively melt metal powders. They found that increasing the laser scanning speed could significantly suppress the formation of brittle intermetallic compounds such as Al5Fe2 and Al13Fe4. They propose that this higher scanning speed results in so-called non-equilibrium solidification, which minimizes solute partitioning leading to weak points in the material. The final product they created displayed a strong adhesive interface.

“In other words, you can’t just put two metals together and expect them to stick together without planning,” said Distinguished Assistant Professor Seungkyun Yim (Northeastern University). “We have to fully understand in situ alloying first. mechanism.

Based on this achievement, they successfully produced the world’s first prototype of a full-scale automotive multi-material part (suspension tower) with customized geometry. The team intends to apply these findings to other metal combinations where similar bonding issues need improvement, which could lead to wider applications.

The results were published in Additive manufacturing November 19, 2024.