Crystallographic-orientation-dependent magnetic properties of Fe–Ni permalloy in-situ alloyed using additive manufacturing

Abstract

The present study focused on improving the magnetic properties of in-situ synthesized Fe–Ni permalloy by engineering the predominant crystallographic texture. To this end, Fe–50 %Ni samples with homogeneous distributions of Fe and Ni were produced using three different rotation strategies through the directed energy deposition method and subsequent heat treatment. According to subsequent microstructural and crystallographic investigations, a pronounced S {123} 〈634〉 texture component and γ-fiber texture were detected in the as-printed sample produced by 67° rotation, resulting in a relatively undesirable magnetic response. Better magnetic properties were achieved in the 90° rotation strategy, with the Cube {001} 〈100〉 and Brass {011} 〈211〉 texture components predominating, and in the no rotation strategy, with the Cube {001} 〈100〉 and Copper {112} 〈111〉 texture components predominating. Heat treatment increased the intensity of the predominant texture components with no significant changes in grain size. On the other hand, short-time heat treatment for the purposes of texture sharpening and dislocation density reduction enhanced the magnetization saturation, coercivity, and Curie temperature values to ~160 emg/g, 1.7 Oe, and ~540 °C, respectively. These findings demonstrate that in comparison with the conventional process, the two-step production approach consisting of crystallographic texture-engineered laser-based in situ alloying additive manufacturing and short-time heat treatment is an efficient route for enhancing the magnetic performance of soft magnetic materials.