Abstract: Magnetostrictive Fe-Ga alloys have captivated substantial focus in biomedical applications because of their exceptional transition efficiency and favorable cytocompatibility. Nevertheless, Fe-Ga alloys always exhibit frustrating magnetostriction coefficients when presented in bulk dimensions. It is well-established that the magnetostrictive performance of Fe-Ga alloys is intimately linked to their phase and crystal structures. In this study, various concentrations of boron (B) were doped into Fe₈₁Ga₁₉ alloys via the laser-beam powder bed fusion (LPBF) technique to tailor the crystal and phase structures, thereby improving the magnetostrictive performance. The results revealed the capacity for quick solidification of the LPBF process in expediting the solid solution of B element, which increased both lattice distortion and dislocations within the Fe-Ga matrix. These factors contributed to an elevation in the density of the modified-D0₃ phase structure. Moreover, the prepared Fe-Ga-B alloys also exhibited a 〈001〉 preferred grain orientation caused by the high thermal gradients during the LPBF process. As a result, a maximum magnetostriction coefficient of 105 ppm was achieved in the (Fe₈₁Ga₁₉)_98.5B_1.5 alloy. In alternating magnetic fields, all the LPBF-prepared alloys showed good dynamic magnetostriction response without visible hysteresis, while the (Fe₈₁Ga₁₉)_98.5B_1.5 alloy presented a notable enhancement of ∼30 % in magnetostriction coefficient when compared with the Fe₈₁Ga₁₉ alloy. Moreover, the (Fe₈₁Ga₁₉)_98.5B_1.5 alloy exhibited favorable biocompatibility and osteogenesis, as confirmed by increased alkaline phosphatase (ALP) activity and the formation of mineralized nodules. These findings suggest that the B-doped Fe-Ga alloys combined with the LPBF technique hold promise for the development of bulk magnetostrictive alloys that are applicable for bone repair applications.

Key words: Fe-Ga alloys, Laser-beam powder bed fusion, Boron doping, Magnetostriction, Cytocompatibility