Atmosphere-induced modulation for manufacturing quality and magnetostriction behavior in FeGa alloys fabricated by laser powder bed fusion

Laser powder bed fusion (LPBF), featuring high processing flexibility holds great promise for fabricating Fe Ga alloys with complex geometries and enhanced magnetostriction for next-generation smart devices. However, the turbulence and spatter in melt pool during LPBF consistently lead to undesired internal defects and degraded magnetostrictive performance. Herein, we proposed an atmosphere-assisted strategy (Ar or N 2 ) during LPBF to simultaneously modulate the manufacturing quality and magnetostrictive performance of Fe Ga alloys. Compared with the commonly used Ar atmosphere, the N 2 atmosphere featuring higher thermal conductivity was partially dissociated under laser irradiation, thereby yielding a wider and shallower melt pool geometry. This flattened melt pool optimized the thermal gradient distribution and promoted a preferred 〈001〉∥BD crystallographic texture, whereas the Ar atmosphere induced a preferred 〈011〉∥BD orientation. As a result, the N 2 -manufactured Fe Ga alloy exhibited a magnetostriction value of ∼79.3 ppm, representing a 25.7% increase over the Ar-manufactured alloy. Furthermore, the N 2 atmosphere facilitated superior manufacturing quality of Fe Ga alloy with a relative density of 99.6%, owing to mitigated heat accumulation and stabilized melt pool behavior. In addition, laser-induced molecular dissociation of N 2 enabled the formation of interstitial nitrogen solid solution within the matix, combining with grain refinement, and defect suppression, synergistically enhancing mechanical performances of the Fe Ga alloys. This study elucidates the modulation mechanisms of atmosphere-induced microstructure in LPBF-manufactured Fe Ga alloys, providing a guidance for developing high-performance magnetostrictive devices.