The National Institute of Standards and Technology (NIST) has demonstrated a metal 3D printing method that stirs molten metal during the print by sending the laser along looping elliptical paths instead of straight lines. This technique change needs no new hardware and could let machines already in service blend alloys that resist mixing. The work, published in the journal Additive Manufacturing, was verified at Argonne National Laboratory's Advanced Photon Source, where the team fused a dense high-entropy alloy called RHEA-19 with a lightweight titanium alloy and watched the two combine into a new alloy in real time.
The technique modifies laser powder bed fusion, in which a laser melts thin layers of metal powder point by point. On a standard print, the beam tracks straight lines, and each brief melt pool blends its ingredients only slightly. NIST researcher Ho Yeung instead programmed the laser to draw loops as it advanced, churning the pool while it stayed liquid. Existing printer firmware couldn’t produce those toolpaths, so the team wrote its own control software.
