Comparing geometry and mechanical performance of as built and Hirtisation® treated Al-Cu-Mg-Ag-Ti-B-Si-Fe rhombic dodecahedron lattices manufactured by laser powder bed fusion

This study investigates the morphological, geometrical, and mechanical characteristics of Al-Cu-Mg- Ag-Ti-B-Si-Fe aluminum alloy lattice structures fabricated via Laser Powder Bed Fusion (LPBF), with emphasis on quasi-static and fatigue mechanical performance. Using the Gibson–Ashby model as a framework, three relative lattice densities (RLDs) were examined in both as-built (AB) and Hirtisation® surface treated (HIRT) conditions. Results confirm that geometric strut waviness is inherent to the LPBF process, affecting both AB and HIRT samples. However, the Hirtisation® treatment notably reduces surface roughness and dross, enhancing fatigue life and surface uniformity. While strut length remains unchanged after post-treatment, a reduced strut diameter (thickness) alters the final density, directly impacting RLD and strength. Quasi-static tests validate the predicted strength–density relationship, with denser lattices exhibiting higher compressive strength. Fatigue testing reveals bending-dominated failure behaviour, marked by crush bands and hybrid brittle-ductile failure mode. These findings deepen understanding of LPBF lattice structures and demonstrate the effectiveness of surface treatment in enhancing fatigue resistance and mechanical performance.