Researchers at the National Institute of Standards and Technology have demonstrated a method for mixing high-entropy alloys during laser powder bed fusion by redirecting the printer's laser into elliptical loop patterns that actively stir the molten pool as it forms. The technique, published in the journal Additive Manufacturing, addresses a persistent obstacle: the constituent metals, differing in density, melting point, and surface tension, naturally separate into discrete patches as the melt cools.
High-entropy alloys, or HEAs, contain multiple elements in roughly equal proportions, sometimes 20 percent each of five different metals, rather than the single base metal with trace additions typical of conventional alloys. That composition improves performance at elevated temperatures, making HEAs candidates for jet engine and nuclear reactor components. "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."
What's new here is the simplicity of the fix. NIST researcher Ho Yeung modified only the laser's travel path, replacing the conventional raster with elliptical loops that stir the melt as it forms. No hardware modifications are required: existing metal printers could be reprogrammed to use the method. "Commercial 3D printer software can't make these patterns," Yeung said. "They are very limited in how the laser's path can be adjusted, so we had to write the software from scratch."
To verify atomic-level mixing, the team combined RHEA-19, a dense high-entropy alloy, with a lightweight titanium alloy and observed solidification in real time. That transition takes under a second, requiring the Advanced Photon Source at Argonne National Laboratory near Chicago, a synchrotron producing X-ray beams roughly 500 billion times brighter than those used in dental imaging.
The team says the approach could support on-demand alloying within the printer itself, using elemental metal powders rather than pre-alloyed feedstocks. Alloy composition could also be varied continuously within a single part. A turbine blade could transition between alloys along its length without welding joints, which introduce weak spots. The paper appeared online January 30, 2026.
