Investigation of the Porosity and Surface Properties of AlSi10Mg Alloy Produced by Selective Laser Melting

Abstract

The surface mechanical properties of AlSi10Mg alloy produced by selective laser melting (SLM) with different laser scan angles α (45°, 67°, 90°) were investigated. Instrumented indentation revealed differences in nanohardness H and elastic modulus E: the α = 90° variant provided the highest nanohardness H = 1.57 ± 0.35 GPa and the lowest maximum indenter penetration depth h_max = 1.2 µm, whereas the α = 67° variant exhibited the highest elastic modulus E = 46.4 ± 3.19 GPa. Scratch testing showed the largest groove depth for the α = 45° sample—8.1 µm, with a friction coefficient μ = 0.79; the smallest groove depth for α = 67°—6.4 µm, μ = 0.73; and intermediate values for α = 90°—6.9 µm, μ = 0.74. Scanning electron microscopy of the hardest sample (α = 90°) revealed surface porosity with predominantly elongated defects: 81% of pores <150 µm, a pore density of 16 pores/mm², a low fraction of pores <50 µm (18.8%), and isolated large cavities up to 457 µm.