Enabling & Support
20/03/2026
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Manufacturing complex metal parts that combine different materials has long posed a significant challenge for 3D printing. When materials with vastly different properties are melted together, the interfaces between them often develop cracks due to high stresses and the formation of brittle phases. A recent ESA Discovery project led by the École Polytechnique Fédérale de Lausanne (EPFL) has demonstrated a promising new approach that could overcome these limitations.
“When we try to assemble different materials within complex shapes using laser 3D printing, high stresses develop in the interfacial regions, together with new phases that may be brittle,” explains Professor Roland Logé, the technical lead for the project. “When stresses are too high, or the new phases are too brittle, the materials are considered ‘non-weldable’. The printing process then leads to cracking, and fails.”
Laser Powder Bed Fusion (LPBF) – a cutting-edge method for fabricating complex metallic parts – works by using a laser to selectively melt thin layers of metallic powder. Attempts to extend this to multi-material printing have typically involved upgrading systems to deposit multiple powders or installing multi-laser systems to melt different materials in a single layer. However, mixing different powders often results in poor interfacial properties, with large intermixing zones creating pores and cracks.
A hybrid solution
The ‘3D printing of multi-materials combining metallic powders with foils, and using beam shaping‘ project investigated a different approach: combining metallic powders with metallic foils rather than mixing powders together. The team focused on combinations of three alloys – 316L stainless steel, Ti-6Al-4V, and Al-12Si – depositing, cutting and welding thin metallic foils onto substrates made of LPBF-consolidated powders or other welded foils.
“ESA funding helped us demonstrate a new way of assembling ‘non-weldable’ metallic materials, by combining powders with foils,” says Logé. “In doing so, we restrict the volume over which brittle phases form, and reduce the magnitude of stresses. This significantly reduces the risk of cracking.”
The project built on previous ESA-supported work on laser beam shaping from the Off-Earth Manufacturing and Construction campaign. This beam shaping capability allows precise control of heating during the printing process. By combining foils with powders, the hybrid approach creates cleaner interfaces between materials, with the ability to produce either sharp boundaries or gradual transitions in composition.
Achieving crack-free interfaces
3D printing of metallic powders and foils
The results demonstrated significant improvements over traditional powder-mixing methods. The hybrid multi-material additive manufacturing approach successfully reduced intermetallic formation and achieved crack-free interfaces between Ti-6Al-4V and Al-12Si. Significant differences in the properties of these two materials make them a particularly challenging combination with a tendency to form brittle compounds.
However, scalability studies revealed important challenges. As the printed area increases, ensuring good contact between the foil and substrate becomes increasingly difficult, whilst residual stresses accumulate as the build height increases, promoting blister formation and delamination.
“This technology addresses the important field of multi-material additive manufacturing and tries to resolve some of the inherent challenges,” says Martina Meisnar, a Materials and Processes Engineer and ESA lead for the project. “The new foil printing method has the potential to improve local microstructures, leading to better mechanical properties at interfaces. Improved cooling paths and beam shaping technologies are expected to lead to significant advantages.”
From concept to application
The work establishes the feasibility of the hybrid manufacturing method whilst highlighting the need for improved thermal control and process modelling to enable reliable large-scale multi-material manufacturing.
Future work will focus on expanding the experimental database necessary to develop a reliable digital twin of the hybrid powder-foil process, coupling experimental investigations with thermal camera analysis. Since processing conditions are highly dependent on geometry and heat dissipation pathways, a comprehensive set of experiments will be conducted to enable accurate numerical predictions.
The potential applications are broad. “Commercial applications could include the fabrication of multi-functional components, in which one material is typically used for its strength, while other materials are added for their heat/electrical conductivity or corrosion resistance,” notes Logé. “Such combinations of properties are very often required in the aerospace, biomedical and energy sectors.”
“This activity was carried out under ESA’s Discovery programme, which is designed to facilitate proof-of-concept studies for highly innovative new technologies,” explains Meisnar. “The team led by EPFL implemented a new approach to 3D printing, where metallic foils were used to avoid some of the disadvantages of more traditional methods. Advanced manufacturing is a key enabling technology for ESA and space industry, as it allows the optimisation of spacecraft part manufacturing.”
The project originated as an idea submitted through ESA’s Open Space Innovation Platform, seeking out promising new concepts for space research, and was funded as a co-sponsored research project by the Discovery element of ESA’s Basic Activities.
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