Simultaneous texture and defect modulation in LPBF-manufactured Fe-Ga alloys for magnetostrictive enhancement

Abstract Magnetostrictive polycrystalline Fe-Ga alloys have sparked widespread interests owing to remarkable magnetic-machinal coupling characteristics but always suffer bottlenecks in concurrent structure-performance customization, essential for high-performance engineering applications. Herein, laser-beam powder bed fusion (LPBF) process featuring interlayer rotation strategy was proposed in this study for the integrated manufacturing of high performance and customized geometry for polycrystalline Fe-Ga alloys. On the one hand, fine magnetostrictive Fe-Ga alloys with complex geometries were firstly manufactured to break through the geometric limitations for magnetostrictive components. On the other hand, the interlayer rotation strategy enabled localized customization of thermal distribution during solidification process and thereby the in-situ modulation of grain growth and defect evolution. Specifically, the LPBF strategy effectively promoted surface planarization, stress relief, and defect healing, and significant reductions in both porosity (from 2.29% to 0.29%) and residual stress (from 319 MPa to 66 MPa) were eventually achieved within the LPBF-manufactured Fe-Ga alloys based on computed tomography (CT) and X-ray stress analysis. Moreover, the LPBF-manufactured polycrystalline Fe-Ga alloys exhibited a unique {001}<100> cube texture according to crystal self-alignment mechanism. As a result, the strong cube texture, together with high densification and relieved stress, contributed to an optimal combination of high magnetostriction (118 ± 5 ppm) and low coercivity (8.6 ± 0.4 Oe) in the LPBF-manufactured polycrystalline Fe-Ga alloys. These findings demonstrated a prospective approach for in-situ texture and defect modulation as well as complex geometric manufacturing of magnetostrictive Fe-Ga alloys, providing a basis for developing next-generation magnetostrictive devices with customized geometry-structure-performance integration.