Researchers at the Massachusetts Institute of Technology (MIT) have developed a new aluminum alloy that could change how lightweight, high-strength parts are 3D printed.

Described in Advanced Materials, the study takes advantage of how metals solidify during laser powder bed fusion, a common form of 3D printing. When aluminum cools rapidly under the laser, its atoms can form metastable structures that do not normally appear in slower casting processes.

Led by S. Mohadeseh Taheri-Mousavi, the research showed that by selecting the right combination of elements, specifically aluminum with small amounts of erbium, zirconium, nickel, yttrium, and ytterbium, they could harness these short-lived structures to create very fine, stable particles that strengthen the metal.

Alongside MIT, the study also saw participation from Carnegie Mellon University, Northwestern University, and Paderborn University in Germany.

Alloy design concept showing how exploiting submicron-meter scale metastable phases due to rapid solidification and the correct composition transforms the length scales of the hardening phase from micro- to nano-meter scale. Image via Advanced Materials Journal / MIT. Alloy design concept showing how exploiting submicron-meter scale metastable phases due to rapid solidification and the correct composition transforms the length scales of the hardening phase from micro- to nano-meter scale. Image via Advanced Materials Journal / MIT.

Stable strength through rapid solidification

In most high-strength aluminum alloys, small particles block the movement of dislocations, which are tiny defects that cause metals to deform. The smaller and more closely spaced these particles are, the stronger the alloy becomes. However, at the high temperatures often used for heat treatment or during service, these particles can grow and coarsen, which reduces the material’s strength. The new alloy avoids this problem.

Under rapid solidification, it first forms submicron-scale metastable phases containing nickel and the rare-earth elements. During heat treatment, these transform into nanometer-scale aluminum-based strengthening phases that stay finely dispersed and resist coarsening even at elevated temperatures.

To design the alloy, the researchers used computer-based materials modeling combined with machine learning. This approach allowed them to test hundreds of thousands of possible combinations of elements to find the one that would best balance strength, stability, and printability.

The final composition, aluminum with about 0.4% erbium, 1% zirconium, and 1.33% nickel, was identified as the best candidate. It could be 3D printed without hot cracking, a common problem that limits the use of many aluminum alloys in additive manufacturing.

Powder made from this composition was successfully printed into dense, crack-free parts. After heat treatment for eight hours at 400 °C, the material reached a tensile strength of 395 MPa, about five times higher than the same composition produced by casting and roughly 50% stronger than the best previously known printable aluminum alloys.

Its hardness matched that of wrought 7075 aluminum, one of the strongest commercial grades, but without the brittleness and cracking that make 7075 difficult to print.

Microscopic analysis showed that the printed alloy contained a dense network of nanometer-scale aluminum-based particles evenly distributed within the metal. These particles remained stable even after extended heating, confirming the alloy’s resistance to coarsening.

The combination of fine grain structure and stable particles accounts for its high strength and temperature stability.

The research team demonstrated that their combined computational and experimental approach can speed up the development of new alloys for additive manufacturing. By coupling modeling, machine learning, and small-scale laser testing before printing full parts, they were able to find a workable and printable composition efficiently within a large design space.

According to the researchers, this method could also be applied to other metals and alloys, including nickel-based superalloys used in aerospace and energy systems. Beyond high-strength aluminum, the same design principle, using rapid solidification to control metastable structures, may lead to printable materials that combine strength, ductility, and heat resistance for a wide range of industrial uses.

The results point to aluminum alloys that are not only strong and heat-resistant but also practical for large-scale AM in aerospace, automotive, and industrial machinery.

Research in high-strength 3D printable aluminum alloys

Away from MIT, Oak Ridge National Laboratory (ORNL) announced testing of a newly developed aluminum alloy for 3D printing and high-temperature automotive components, called DuAlumin 3D. The alloy showed superior printability and performance compared to conventional aluminum grades, which often crack during laser powder bed fusion, while still maintaining excellent thermal properties.

Its resistance to cracking and high-temperature stability make it a strong candidate for lightweight, fuel-efficient engine parts. According to ORNL researchers, DuAlumin 3D could also find use in aerospace and heat exchanger applications, enabling stronger, lighter, and more heat-tolerant 3D printed components for next-generation industrial systems.

Eight years ago, HRL Laboratories developed a 3D printing technique for high-strength aluminum alloys such as Al7075 and Al6061, previously considered non-weldable due to severe hot cracking during laser melting. Published in Nature, the method used nanoparticle functionalisation, where alloy powders were coated with zirconium-based nanoparticles that acted as nucleation sites during solidification, eliminating cracking and preserving full alloy strength.

The team employed Citrine Informatics to identify suitable nanoparticles through data-driven materials selection. The process was scalable, low-cost, and could extend to other difficult-to-print alloys, including high-strength steels and nickel-based superalloys, broadening additive manufacturing applications in aerospace and industry.