Tailoring grain growth and nanoprecipitation behavior via laser-beam powder bed fusion and aging for magnetostrictive enhancement of Fe-Ga-B alloys

Fe-Ga-based alloys are considered promising magnetostrictive candidates because of their high permeability and favorable mechanical properties. However, currently developed Fe-Ga-based alloys often suffer from a limited capability for microstructure manipulation, which restricts their magnetostrictive performance. To address this limitation, this study proposes a novel strategy combining laser-beam powder bed fusion (LPBF) and aging treatment to modulate the microstructure and enhance magnetostrictive properties of Fe-Ga-B alloys. Considering the positive influence of B element on magnetostrictive property and ductility, B-doped magnetostrictive Fe-Ga alloys were prepared via the LPBF process and then aged at 600°C for varying times (1, 2, and 3 h, respectively). The LPBF process, characterized by high thermal gradients and rapid solidification, produced a microstructure featuring oriented grains and sparse m-D03 nanoprecipitates embedded in an A2 matrix. After the aging treatment, sufficient nucleation and growth of nanoprecipitates were enhanced. Specifically, the sample aged for 2 h developed a high density of larger m-D03 nanoprecipitates.This optimized microstructure yielded a high magnetostrictive strain of (109±12) ppm and a substantially reduced saturation field—decreased by ~49.1% compared to the as-fabricated state—primarily due to the synergistic effect of the texture and the dense nanoprecipitates. Moreover, all the prepared alloys exhibited good soft-magnetic characteristics and comparable mechanical properties. Therefore, the combination of LPBF and aging treatment offers a promising route for tailoring the macro/microstructure and performance of magnetostrictive Fe-Ga alloys for diverse applications.