Improving the Magnetic Properties of Electrodeposited Fe-55wt%Ni Alloy via Abnormal Grain Growth Induced by Second-Phase Particles

In this study, pulse reverse current electrodeposition was employed to fabricate Fe-55 wt%Ni alloy. Abnormal grain growth induced by the precipitation of second-phase particles during annealing resulted in a coarse-grained electrodeposited Fe-55 wt%Ni alloy. The grain evolution process during annealing was investigated, and the temperature for abnormal grain growth was determined through the high-temperature confocal microscopy technique. Subsequently, the mechanism of abnormal grain growth was investigated. The results suggest that abnormal grain growth occurs at approximately 1003 K, attributed to the preferential growth of (110) oriented grains due to local strain energy changes caused by the precipitation and coarsening of the second-phase particles (MnS). The preferred orientation of the grains transitioned from (111) to (110). Annealing at 1073 K for 2 h resulted in an average grain size increase to approximately 200 μm. Under these conditions, the magnetic properties of the alloy reached optimal levels, with a magnetization saturation strength of 186.7 emu g−1 and a coercivity of less than 1 Oe. This research presents a novel approach to preparing coarse-grained electrodeposited Fe-Ni alloys, significantly enhancing their magnetic properties.