Researchers from the National Institute of Standards and Technology (NIST) have discovered special atomic patterns, called quasicrystals, which increase the strength of 3D-printed aluminum alloys. This discovery makes it possible to use these alloys in lightweight, high-strength objects such as airplane parts.
Challenges of 3D-Printing Aluminum
In the powder bed fusion method of 3D printing, a powerful laser moves over a thin layer of aluminum powder, melting the material and forming layers of metal into a solid shape. This is a powerful production method capable of making high-strength, complex components that couldn’t be produced otherwise, such as the 3d-printed fuel nozzles developed by General Electric (GE) for airplane engines in 2015. The new nozzle simplified the design, which previously was assembled from 20 separate pieces as well as being 25% heavier. Since developing this new design, GE has reportedly printed tens of thousands of these fuel nozzles, demonstrating the commercial success of the technology.
However, only a limited number of alloys can be used in 3D printing. Aluminum typically melts at temperatures of around 700°C. However, in diffusion bed 3d printing, the temperature of the laser is up to 2,470°C, which changes the properties of the metal due to the faster speed at which aluminum heats up and cools down.
“High-strength aluminum alloys are almost impossible to print,” said Fan Zhang, a NIST physicist on the project and a co-author on the paper. “They tend to develop cracks, which make them unusable.”
Addressing the Challenge
HRL Laboratories partnered with UC Santa Barbara to develop a high-strength aluminum alloy that could be 3D printed in 2017. The team discovered that by adding zirconium to the aluminum powder, cracking could be prevented during 3D printing, resulting in a strong alloy.
“In order to trust this new metal enough to use in critical components such as military aircraft parts, we need a deep understanding of how the atoms fit together,” said Zhang. So, the NIST researchers set out to study the aluminum-zirconium alloy on the atomic scale to better understand what enabled the metal’s strength.
While examining a sliver of the new alloy through an electron microscope, Andrew Iams, a materials research engineer at NIST and an author on the paper, noticed that the atoms were arranged in an extremely unusual pattern. “That’s when I started to get excited,” said Iams, “because I thought I might be looking at a quasicrystal.”
Quasicrystals were once thought impossible, but were originally discovered by Dan Shechtman, a materials scientist from Technion-Israel Institute of Technology, while on a sabbatical at NIST in the 1980s. While traditional crystals are made out of any solid made of atoms or molecules in repeating patterns (with only 230 possible ways for atoms to form these patterns), quasicrystals have a unique shapes that forms a pattern that never repeats. At the time, many scientists thought his research was flawed because the new crystal shapes did not follow the normal rules for crystals. However, further research proved beyond a doubt that this new type of crystal existed. Shechtman’s research revolutionized the science of crystallography, winning him the 2011 Nobel Prize in Chemistry.
Now, Iams has found quasicrystals in a new 3D-printed aluminum-zirconium alloy. When he looked at the crystals from just the right angle, he saw that they had fivefold rotational symmetry — meaning there are five ways to rotate the crystal around an axis so that it looks the same. “Fivefold symmetry is very rare. That was the telltale sign that we might have a quasicrystal,” said Iams. “But we couldn’t completely convince ourselves until we got the measurements right.”
However, once it was discovered, Iams had to prove they had a quasicrystal, which involved rotating the crystal under the microscope, showing that is had threefold symmetry and twofold symmetry from two different angles. “Now that we have this finding, I think it will open up a new approach to alloy design,” said Zhang. “We’ve shown that quasicrystals can make aluminum stronger. Now people might try to create them intentionally in future alloys.”
Further research at NIST proved that these quasicrystals were making the alloy stronger. Perfect crystals in metals are weak, because the perfect pattern makes it easier for the atoms to slip past each other, which is what causes the metal to stretch or break. Quasicrystals break up the regular pattern of the aluminum crystals, causing defects that make the metal stronger.
According to the researchers, understanding this aluminum on the atomic scale will enable a whole new category of 3D-printed parts, such as airplane components, heat exchangers and car chassis. It will also open the door to research on new aluminum alloys that use quasicrystals for strength.
To learn more about this NIST research, read “Microstructural Features and Metastable Phase Formation in a High-Strength Aluminum Alloy Fabricated Using Additive Manufacturing,” by A.D. Iams, J.S. Weaver, B.M. Lane, L.A. Giannuzzi, F. Yi, D.L. LaPlant, J.H. Martin, and F. Zhang, which was published in Journal of Alloys and Compounds on April 7, 2025 (DOI: 10.1016/j.jallcom.2025.180281).