Better metals, with help from a small square with billions of holes
Despite significant advances in technology, knowing the atomic arrangement of metals in their microstructure—which define their strength, deformability, and other properties—is still tricky. In a new study, Yale researchers show that a mold about half the size of a fingernail could solve for that, and lead to the development of stronger and higher performing materials for airplanes and other uses. Their results are published in Nature Communications.
When molten metals cool, crystals form throughout. They eventually grow until they meet each other and form millions of what are known as grains, disrupting the material’s overall atomic pattern.
“These grains are about the diameter of a human hair, and they're arranged in different orientations,” said Jan Schroers, the Robert Higgin Professor of Materials Science & Mechanical Engineering, who led the study.
The chemistry and the orientation of the grains control the actual properties of the material. Smaller grains make for stronger metals, for instance, and larger grains make for more deformable metals. Because the pattern of grains isn’t uniform throughout a piece of metal, different properties can show up in different places in the same piece of metal. That makes it difficult to tailor a piece of metal to a specific use.
Why it matters
“People are very interested in this, for the nuclear industry and also for high-temperature jet engines and gas turbines—that is, to have materials that don't deform at high temperatures,” Schroers said.
If scientists had a clearer understanding and better control of the atomic structures of various metals, they could better understand, predict, and optimize materials for different purposes.
“We want a way to develop better materials. We want to make a material and be able to say ‘We see this is the weakness,’ and then we can think about how we can reduce that weakness.”
The problem
There’s a tradeoff between the two most common methods of analyzing a metal’s overall structure and properties, and neither produces a fully satisfying result.
Transmission electron microscopy (TEM) is one of the most prominent means of studying these structures. With TEM, an electron beam is shot into a piece of metal, getting a very clear snapshot of a very small area of that piece of metal. However, grain structures change throughout the same piece of metal, so that snapshot doesn’t give you anything close to the full picture.
“Using TEM may take forever, because it just allows you to look at one really, really small part of the metal,” Schroers said. “Without more information, you don't know where to put it. You have a billion possibilities.”
Conversely, researchers can apply a mechanical test to an entire piece of metal to determine its strength and other properties. “But in that case, you don't really know what is going on microscopically,” Schroers said.
The solution
The solution comes in the form of a small, square mold with billions of nano-sized holes. The process involves heating up a piece of metal about the size of the mold and then pressing it against the mold. The metal passes through the holes, forming nanorods. What caught the researchers’ attention when they first did this was that the nanorods varied dramatically in length, even though they applied the same pressure and temperature throughout the piece of metal. Co-author Dr. Arindam Raj suggests that the imprint on the mold provides a “picture” of the microstructures.
Knowing where the nanorods were longer and shorter, they could see at a resolution of about 2.5 nanometers what the metal’s properties were over a large area and connect properties with its atomic structure at the location.
“So our technique closes this gap,” Schroers said. “We can measure over macroscopic dimensions that you can see with your naked eyes, but we have very high microscopic resolution. This imprint gives us the characteristics of the material. It gives us a new tool, like a microscope.”
Photo: The Instron testing machine used to press metal samples against the nanomold, forming the nanorod arrays central to the new imaging technique (Photo: Michael Aderibigbe, Schroers Lab).
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Published Date
Jul 29, 2026
