Surface smoothing and periodic microstructuring of additively manufactured scalmalloy® by sequential continuous-wave polishing and direct laser interference patterning

Laser Powder Bed Fusion is gaining industrial prominence due to its ability to create complex parts with reduced material waste. Scalmalloy® stands out as a possible replacement for titanium, offering high strength and thermal conductivity while maintaining low component weight. Nevertheless, parts produced by this method normally exhibit high surface roughness, characterized by partially melted particles and surface irregularities. In addition, low surface roughness is also a prerequisite for the further fabrication of well-defined microstructures that can enhance surface functions based on mimicking natural examples. This work combines surface smoothing by continuous-wave laser re-melting with the fabrication of periodic textures using Direct Laser Interference Patterning to tailor surface topography. Initial laser polishing trials achieve a substantial reduction of as-built Ra roughness from approximately (Ra) ~14 μm to 1–2 μm but generated subsurface pores. The porosity is mitigated by adjusting laser power and feed rate. The polished samples are subsequently microstructured by DLIP using a picosecond pulsed laser, producing structure depths up to 3.0 μm with a homogeneity of approximately 82%. Finally, the performance of the combined process is analyzed in terms of energy consumption and target surface parameters to improve process sustainability. • CW laser polishing reduces Scalmalloy surface roughness from ~14 μm to ~1.5–2 μm at low cumulative fluence. • Subsurface porosity forms in Scalmalloy® at high laser power during polishing. • DLIP using a picosecond pulsed laser produces 6 μm-period line textures with depths up to ~3 μm and ~80% homogeneity on polished surfaces. • Pattern quality deteriorates when the pulse-to-pulse overlap during DLIP exceeds ~99%. • A multi-objective cost function enables energy-based selection of parameters for sequential laser polishing and DLIP.