Improving Surface Finish of Al–Mg–Sc–Zr Alloy by Thermodynamics Control and Process Optimization During High‐Precision Microlaser Powder Bed Fusion (μ‐LPBF)

High‐precision microlaser powder bed fusion (μ‐LPBF) contributes to fabricate complex microcomponents by refining processing parameters. The influence of μ‐LPBF scanning parameters on the densification behavior, molten pool features, microstructure evolution, and surface morphology of the Al–Mg–Sc–Zr alloy is investigated. The Al–Mg–Sc–Zr specimens are successfully fabricated by μ‐LPBF with relative densities of 99.0–99.8%. The μ‐LPBF‐processed specimens exhibit a small molten pool size with a width ranging from 36 to 65 μm and a depth ranging from 9 to 21 μm. Through the thermodynamic control of the molten pool in the mesoscale, a continuous and stable melted track is obtained at the optimized laser scanning speed of 1000 mm s −1 . The mean grain size of μ‐LPBF is 0.714–1.156 μm smaller than that of the conventional laser powder bed fusion (c‐LPBF) ones. With the increase in scanning speed, the surface roughness first shows a downward trend until reaches the minimum ( Ra of 4.087 μm) at the scanning speed of 1000 mm/s, which then increases ( Ra of 7.002 μm) when the scanning speed further increases. The optimized processing parameters are laser power of 50 W, scanning speed of 1000 mm s −1 , layer thickness of 10 μm, and hatch distance of 25 μm for μ‐LPBF of Al–Mg–Sc–Zr alloy.