NIST researchers programmed a metal 3D printer's laser to trace repeated loops, stirring metals that ordinarily separate as the molten pool cools, the agency reported.
The method targets a basic additive-manufacturing problem: metals with different densities, melting points and surface tensions can segregate into weak, uneven regions instead of forming a uniform alloy.
Rather than tracing straight lines, the team made the laser draw loop-the-loops as it crossed the powder bed. That motion actively mixed the tiny molten pool while the material was being printed.
NIST said commercial printer software could not generate the needed path, so the researchers wrote new controls. The approach does not require major new printer parts, suggesting existing systems could eventually be adapted.
The test combined RHEA-19, a dense refractory high-entropy alloy, with a lighter titanium alloy. High-entropy alloys use several metals in relatively similar proportions and can be difficult to mix uniformly by conventional casting.
Verification required watching dense metal solidify in less than a second. At Argonne National Laboratory's Advanced Photon Source, the team used synchrotron X-ray diffraction to track atomic structure in real time.
Electron microscopy of the solidified material provided a second check. NIST said the measurements showed that the looping scan successfully mixed the two materials into a new alloy.
The researchers see a possible path toward on-demand alloys made from elemental or feedstock powders, reducing the need to stock a separate pre-alloyed powder for every composition and permitting graded parts without welds.
That remains a research prospect, not a production guarantee. The demonstration involved selected materials and laboratory equipment; repeatability, scale, qualification, software controls and performance testing would be required before safety-critical manufacturing use.