Laser additive processing of functionally-graded Fe–Si–B–Cu–Nb soft magnetic materials

Laser additive manufacturing is a novel tool for processing compositionally-graded alloys that are challenging to process via a conventional route. This article discusses a novel combinatorial approach for assessing composition–microstructure–magnetic property relationships, using laser deposited compositionally-graded Fe–Si–B–Nb–Cu alloys (by changing the silicon to boron ratios). The microstructure of Fe–Si–B–Nb–Cu alloys with a lower Si to B ratio consists of dendritic α-Fe₃Si grains, with B and Nb partitioning to the inter-dendritic regions, resulting in the formation of Fe₃B grains. As the Si/B ratio increases, the (Fe, Nb) enriched eutectic phase was observed along with α-Fe₃Si grains; and no Fe₃B was observed. These microstructural changes with varying Si/B ratios significantly affect the magnetic properties of these laser-deposited soft magnetic alloys.