  The widespread application of metal additive manufacturing (AM) is limited by
the ability to control the complex interactions between the energy source and
the feedstock material. Here we develop a generalizable process to introduce
nanoscale grooves to the surface of metal powders which increases the powder
absorptivity by up to 70% during laser powder bed fusion. Absorptivity
enhancements in copper, copper-silver, and tungsten enables energy efficient
manufacturing, with printing of pure copper at relative densities up to 92%
using laser energy densities as low as 82 J/mm^3. Simulations show the enhanced
powder absorptivity results from plasmon-enabled light concentration in
nanoscale grooves combined with multiple scattering events. The approach taken
here demonstrates a general method to enhance the absorptivity and printability
of reflective and refractory metal powders by changing the surface morphology
of the feedstock without altering its composition.

Optics;Materials Science