NIST Researchers Discover a New Way to Whisk Alloys Together With Lasers

Like modern-day alchemists, metallurgists are constantly discovering and perfecting recipes for better alloys. A crucial step in those recipes is to get different metals to mix evenly. Unveiling a new utensil for the metallurgical kitchen, researchers at the National Institute of Standards and Technology (NIST) have invented a way to whisk metal with a laser as it's 3D-printed, opening a new route for creating hard-to-make metal alloys. To verify their success, they also developed a way to watch changes in the metal using X-rays as they melted and solidified in a fraction of a second.

Humans ask our metals to do a lot of different things. We sometimes want them to be strong, corrosion-resistant, lightweight, inexpensive, heat-resistant or able to perform in radioactive environments. Luckily, researchers can fine-tune metal properties by blending metals together into alloys. Thousands of metal alloys have been created throughout history, from bronze swords to steel girders to the aluminum alloys used in aircraft.

Over the last 20 years, researchers have begun developing a new class of alloys called "high-entropy alloys" (HEAs). At the atomic level, HEAs have an unusual arrangement, which can improve their performance at high temperatures. HEAs can be ideal for applications that need the material to stay strong at high temperatures, such as jet engines or nuclear reactors. But they're also more difficult to make.

Traditional alloys are mostly made of just one base metal with small amounts of other elements added. Basic steel, for example, is almost entirely iron with small amounts of carbon. Adding other elements such as nickel or chromium can make the steel stronger or more corrosion-resistant.

HEAs break that pattern; they contain more metals in more equal proportions than traditional alloys. So, an HEA might be made up of 20% each of five different metals.

"HEAs need to be mixed down to the atomic level," said Fan Zhang, the NIST physicist who co-led the project. "It takes extra effort to get metals to blend together in those ratios."

Different metals have different densities, melting points, surface tension and other properties that cause them to separate into blotches as the molten metal cools. Like oil and water, the components of the alloy naturally tend to separate into a patchwork of distinct regions that weakens the metal overall.

"It's difficult to make HEA parts with traditional methods like casting," said Zhang, "But we believe metal 3D printing could be a solution." As described in the journal Additive Manufacturing, the NIST-led team demonstrated a new way to 3D-print these elusive alloys by whisking them together with the printer's laser. And since this method can bring together the discordant metals of HEAs, it could also be used to bring together the more harmonious metals of conventional alloys.

Metal 3D Printing

Metal 3D printing is a promising new technology. It allows engineers to create metal objects that use less material, require fewer parts or have complicated shapes that can't be made any other way. The technique is already finding its way into lightweight rocket engines, automotive factories and even bathroom faucets.

The most common type of metal 3D printing is called laser powder bed fusion. In this process, a powerful laser traces out a pattern on a layer of fine metal powder. As the laser passes, for a fraction of a second the metal powder melts together into a tiny puddle, smaller than a ladybug's eye. Within that puddle, different elemental metals will mix together a little because of the heat, but not enough for a tricky alloy like an HEA. So NIST researcher Ho Yeung began to look for a new way to actively stir the metal as they printed it.

Their solution was relatively simple. Instead of having the laser trace straight lines, Yeung and his team directed the laser to draw loop-the-loops as it moved, stirring the metal together as it was melting.

"Commercial 3D printer software can't make these patterns," explained Yeung. "They are very limited in how the laser's path can be adjusted, so we had to write the software from scratch." However, since this solution doesn't require any new major parts, existing metal 3D printers could be programmed to use this technique.

To prove their method worked, the researchers put it through a challenging test by combining two metals that are normally extremely hard to mix together: a dense high-entropy alloy called RHEA-19 and a lightweight titanium alloy. They layered the metals next to each other and then passed the looping laser across the edge of the layers. Then they checked to see if the metals effectively combined into a new alloy.

To do that, they needed to examine the atomic structure of the metal in real time as it cooled from molten liquid to solid metal. This is an extremely challenging measurement because the metals are dense and that solidification happens in less than a second. The NIST team needed a powerful X-ray machine. They partnered with the Advanced Photon Source (APS) at Argonne National Laboratory, near Chicago. The APS is a ring-shaped machine larger than a football stadium that creates incredibly bright X-ray beams. Those beams are roughly 500 billion times brighter than the X-rays used at a dentist's office. "The APS is one of the few photon sources in the world powerful enough to allow us to perform this type of measurement," said Zhang.

As the X-ray beam from the APS passed through the metal, X-ray photons were deflected by metal atoms, creating a distinctive pattern on the other side. That pattern could then be decoded to see how the atoms were arranged and watch them change in real time. The researchers also used electron microscopes to examine the final product after it was completely solid. After using these advanced measurement methods, the researchers proved that their laser whisk worked, opening the door for printing these alloys more effectively.

One of the most challenging parts of this research was developing a way to see what was happening inside the metal on the atomic level as it cooled. For this research project, NIST pioneered a way to do just that using X-ray diffraction, a method where X-rays are passed through the metal, bouncing off some of the atoms. Then the X-ray patterns on the other side are analyzed to determine how the atoms are arranged.

Alloys on Demand

In the future, this technique could also be used to instantly create other alloys, not just HEAs. This could reduce costs and create more flexibility for metal 3D printing. Currently, each metal powder used in 3D printing can only be used to make one specific alloy. If you want to be able to print a dozen different alloys, you may need a dozen different alloy powders.

In the same way an office printer only has four inks and then mixes them to make any color, this new stirring method could be an effective way to combine elemental metal powders into alloys within the printer. This would make metal 3D printing less expensive and more versatile. It could even be used to slowly alter alloys throughout metal parts. The blade of a jet turbine could be 3D-printed out of several different metals without the need for welding, which might create weak spots.

"We want to accelerate alloy making," said Yeung. "Metal 3D printing has the potential to make parts that used to be impossible."

Paper: Ho Yeung, Jordan Weaver, Andre Ponsot, Junaid Dar, Yisong Zhang, Dong Lin, Andrew Chuang, Michael C. Gao and Fan Zhang. Laser stirring with elliptical scanning enables on-demand alloying in additive manufacturing. Additive Manufacturing. Published online Jan. 30, 2026. DOI: 10.1016/j.addma.2026.105101