Stabilizing Fe-based nanocrystalline alloys via a high-entropy strategy

Abstract

Fe-based nanocrystalline alloys with unique dual-nano-phase structure and superior magnetic softness have aroused tremendous interest, yet they generally suffer from the harsh annealing process due to the poor thermal stability. In this study, a high-entropy strategy was proposed to enhance the soft-magnetic property and nanostructure stability of Fe-based nanocrystalline alloys by adding P and C elements in the FeCuSiBPC alloy system. This alloying approach by complicating the composition will greatly increase the mixing entropy, which significantly increase the frequency factor for the formation of α-Fe grains and activation energy for the formation of compounds, which on one hand enhance the competition and soft-impingement effects due to the increased number density of α-Fe grains, and on the other hand hinder the precipitation of compounds in the intergranular amorphous interphase due to the improved crystallization resistance. These both contribute to a thermodynamically and kinetically stable dual-nano-phase structure with fine α-Fe grains embedded in amorphous matrix. Following this strategy of nanostructure stabilization by tuning the compositional complexity, FeCuSiBPC alloy with enlarged processing window and enhanced soft-magnetic properties were successfully obtained. This high-entropy strategy can be applied in a verity of alloy systems to develop high performance nanocrystalline alloys with excellent thermal stability suitable for large-scale industrial processing.