Abstract: Fe-based amorphous/nanocrystalline alloys have demonstrated considerable potential in magnetically driven implant applications due to their impressive soft magnetic properties. However, traditional preparation methods are usually limited by either simplistic structures/dimensions or composition-induced biosafety issues. In the present study, FeSiB amorphous/nanocrystalline alloys were fabricated by laser-beam powder bed fusion (LPBF), and the effects of LPBF process parameters on the microstructure, magnetic and mechanical properties of the resulting alloys were systematically investigated. The results showed that relatively higher energy densities could reduce the internal defects and promote the alloy density but led to decreases in the amorphicity of FeSiB alloys on account of more heat diffusion, indicating a competitive microstructural evolution during LPBF process. Moreover, α-Fe(Si) and Fe₂B nanocrystalline grains were found to concentrate in the heat-affected zones due to the large thermal gradients in LPBF and exhibit larger sizes at higher energy density. The co-existence of amorphous/nanocrystalline phases endowed FeSiB alloys with high saturation magnetization (M_s) due to their exchange coupling, while the increase of grain sizes and internal defects both caused undesirable high coercivity (H_c). As a result, the LPBF-fabricated FeSiB amorphous/nanocrystalline alloys exhibited an optimal balance between density (6.17 g/cm³) and amorphicity (55 %), which contributed to favorable soft magnetic properties with a high M_s (167.56 emu/g) and a low H_c (60.6 Oe), as well as excellent mechanical properties (compressive strength 501.5 MPa and hardness 14.58 GPa). These findings demonstrated the potential of LPBF for the fabrication of Fe-based soft magnetic alloys with tailorable structures and properties.

Key words: FeSiB amorphous/nanocrystalline alloys, Laser-beam powder bed fusion, Microstructure, Soft magnetic, Mechanical properties