Quasicrystals, once considered impossible, were found in a 3D-printed aluminum alloy – and they make it stronger. This could change how we design aircraft and car components.
- Researchers at NIST discovered quasicrystals, rare, non-repeating atomic structures, in 3D-printed aluminum alloys.
- These quasicrystals were found to strengthen the metal, making it more suitable for lightweight, high-performance parts like those used in airplanes.
- Quasicrystals were first discovered at NIST in the 1980s, a breakthrough that challenged long-held scientific beliefs, and earned a Nobel Prize in Chemistry in 2011.
Strange Patterns at the Atomic Scale
While examining a sliver of a new aluminum alloy under an electron microscope, materials research engineer Andrew Iams noticed something unusual. At the atomic scale, the atoms were arranged in a highly irregular pattern—one that didn’t follow the typical repeating structure of most crystals. “That’s when I started to get excited,” said Iams, a materials research engineer, “because I thought I might be looking at a quasicrystal.”
His instincts were right. Iams and his colleagues at the National Institute of Standards and Technology (NIST) confirmed that the alloy contained quasicrystals, rare atomic structures that don’t repeat like conventional crystals. Even more surprising, they found that these quasicrystals actually increased the alloy’s strength. The team published their findings in the Journal of Alloys and Compounds.
The alloy had formed during metal 3D printing, a manufacturing process that uses high-powered lasers to fuse metal powder into complex shapes. Studying this material at the atomic level could lead to a new class of 3D-printed components, from aircraft parts to heat exchangers and car frames. It also opens the door to designing new aluminum alloys that intentionally incorporate quasicrystals for added strength.
What Are Quasicrystals?
Quasicrystals are like ordinary crystals but with a few key differences.
A traditional crystal is any solid made of atoms or molecules in repeating patterns. Table salt is a common crystal, for example. Salt’s atoms connect to make cubes, and those microscopic cubes connect to form bigger cubes that are large enough to see with the naked eye.
There are only 230 possible ways for atoms to form repeating crystal patterns. Quasicrystals don’t fit into any of them. Their unique shape lets them form a pattern that fills the space, but never repeats.
Dan Shechtman, a materials scientist at Technion-Israel Institute of Technology, discovered quasicrystals while on sabbatical at NIST in the 1980s. Many scientists at the time thought his research was flawed because the new crystal shapes he found weren’t possible under the normal rules for crystals. But through careful research, Shechtman proved beyond a doubt that this new type of crystal existed, revolutionizing the science of crystallography and winning the chemistry Nobel Prize in 2011.
Working in the same building as Shechtman decades later, Andrew Iams found his own quasicrystals in 3D-printed aluminum.
How Does Metal 3D Printing Work?
There are a few different ways to 3D-print metals, but the most common is called “powder bed fusion.” It works like this: Metal powder is spread evenly in a thin layer. Then a powerful laser moves over the powder, melting it together. After the first layer is finished, a new layer of powder is spread on top and the process repeats. One layer at a time, the laser melts the powder into a solid shape.
More than 40 metal 3D printers at a GE Aviation plant in Auburn, Alabama, have produced more than 30,000 fuel nozzles for the high performance LEAP engine. In this ASME video, the engineer who was given the task to design the fuel nozzle describes how he took on the challenge.
3D printing creates shapes that would be impossible with any other method. For example, in 2015 GE designed fuel nozzles (see video above) for airplane engines that could only be made with metal 3D printing. The new nozzle was a huge improvement. Its complex shape came out of the printer as a single lightweight part. In contrast, the previous version had to be assembled from 20 separate pieces and was 25% heavier. To date, GE has printed tens of thousands of these fuel nozzles, showing that metal 3D printing can be commercially successful.
One of the limitations of metal 3D printing is that it only works with a handful of metals. “High-strength aluminum alloys are almost impossible to print,” says NIST physicist Fan Zhang, a co-author on the paper. “They tend to develop cracks, which make them unusable.”
Extreme Temperatures Create New Properties
Normal aluminum melts at temperatures of around 700 degrees C. The lasers in a 3D printer must raise the temperature much, much higher: past the metal’s boiling point, 2,470 degrees C. This changes a lot of the properties of the metal, particularly since aluminum heats up and cools down faster than other metals.
In 2017, a team at HRL Laboratories, based in California, and UC Santa Barbara discovered a high-strength aluminum alloy that could be 3D printed. They found that adding zirconium to the aluminum powder prevented the 3D-printed parts from cracking, resulting in a strong alloy.
The NIST researchers set out to understand this new, commercially available 3D-printed aluminum-zirconium alloy on the atomic scale. “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.
The NIST team wanted to know what made this metal so strong. Part of the answer, it turned out, was quasicrystals.
Quasicrystals Disrupt Weak Points
In metals, perfect crystals are weak. The regular patterns of perfect crystals make it easier for the atoms to slip past each other. When that happens, the metal bends, stretches or breaks. Quasicrystals break up the regular pattern of the aluminum crystals, causing defects that make the metal stronger.
When Iams looked at the crystals from just the right angle, he saw that they had fivefold rotational symmetry. That means 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.” To confirm they had a quasicrystal, Iams had to carefully rotate the crystal under the microscope and show that it also had threefold symmetry and twofold symmetry from two different angles.
The Future of Alloy Design
“Now that we have this finding, I think it will open up a new approach to alloy design,” says Zhang. “We’ve shown that quasicrystals can make aluminum stronger. Now people might try to create them intentionally in future alloys.”
Reference: “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, 7 April 2025, Journal of Alloys and Compounds.
DOI: 10.1016/j.jallcom.2025.180281
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