Additive Manufacturing of AlNiCo5 Hard Magnetic Alloy Through Laser Powder Bed Fusion: A Single Scan Track Study of Microstructure and Nanomechanical Integrity

This paper studies the influence of laser power and scanning speed through single laser scan tracks on AlNiCo5 and SS 304 substrates. Track morphologies and melt pool geometries were assessed to determine the prevailing melting modes. Cracking was observed only on AlNiCo5 substrates, while SS 304 substrates exhibited crack-free tracks, highlighting the advantages of its ductile FCC structure. Optimal laser powder bed fusion process parameters for AlNiCo5 fabrication were identified as 190 W and 600–900 mm/s for stable conduction melting, while for higher laser power processing, 270 W and 600–800 mm/s provided stable transition melting. Microhardness measurements, nanoindentation, and energy-dispersive X-ray spectroscopy were employed to analyze mechanical properties and compositional variation within the melt pools. Increased laser power led to noticeable dilution of the SS 304 substrate into the AlNiCo5 tracks, reducing the melt pool’s overall microhardness due to altered chemical composition. Nanoindentation analysis further confirmed localized mechanical heterogeneity within the melt pool, with Co- and Al-rich zones showing elevated nanohardness, elastic modulus, and resistance to plastic deformation (H/Er, H3/Er2), while substrate-diluted areas (Cr-enriched) exhibited softening linked to BCC-to-FCC phase transformation.