Additively manufactured Ni-15Fe-5Mo Permalloy via selective laser melting and subsequent annealing for magnetic-shielding structures: Process, micro-structural and soft-magnetic characteristics

•SLM AM was employed to fabricate Ni-15Fe-5Mo Permalloy parts.•Hierarchical and anisotropic microstructures were generated via SLM.•The magnetic anisotropy of as-printed Permalloy by SLM was found.•The synthetical magnetic properties of as-printed Permalloy were improved. Selective laser melting (SLM) and subsequently recrystallization annealing was employed to additively manufacture Ni-15Fe-5Mo Permalloy magnetic shielding structures for applications. The experimental works of SLM process optimization were completed to obtain the tailored parameters for acquiring samples with a high relative bulk density of 99.86% and a relatively low surface roughness. The hierarchical and anisotropic microstructure characteristics and their effects on the mechanical and soft magnetic properties of SLM-printed and subsequently annealed samples were focused on to explain some mechanism issues in terms of the comparisons on those before and after the anneal. The recrystallization annealing did not significantly alter the preferred orientations of the crystallographic textures. The SLM-printed microstructural evolution, including residual-stress relief, grain boundary density variation, elimination of cellular substructural walls, and composition re-homogenization, contributed to the promotion of the synthetical magnetic characteristics in the Ni-15Fe-5Mo Permalloy. The anisotropy characteristic of as-printed and subsequently annealed microstructures induced the typical phenomenon of magnetic anisotropy exhibiting when the magnetic induction was changed corresponding to the SLM building direction.