Grain refinement in Fe-rich FeSiB(P)NbCu nanocomposite alloys through P compositional modulation

The progressive addition of P in Fe-rich FeSiB(P)NbCu nanocomposite alloy leads to grain refinement of alpha-Fe nanocrystals i.e, dense nucleation and grain growth inhibition. The P addition leads to linear reduction of alpha-Fe nanocrystallite size (D) and increases nucleation density (N-d) from similar to 30 nm and 2.5 x 10(22) (0 at% P) to similar to 15 nm and 0.9 x 10(23) for (8 at% P). The refined microstructure leads to coercivity reduction from 74 A/m (0 at% P) to 9.4 A/m (8 at% P), in agreement with Random-Anisotropy Model. The P assisted synergistic grain refinement mechanism is explained in the context of crystallization activation energy, selective solute re-distribution and enhanced stabilization of intergranular amorphous matrix. The 4 at% P alloy shows optimal soft-magnetic properties of 10.2 A/m and 1.64 T. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The addition of P in FeSiB(P)NbCu nanocomposite alloy leads to grain refinement of alpha-Fe nanocrystals, resulting in reduced coercivity and enhanced soft-magnetic properties. This synergistic grain refinement mechanism is explained by the activation energy of crystallization, selective solute re-distribution, and enhanced stabilization of intergranular amorphous matrix. The optimal soft-magnetic properties are achieved in the 4 at% P alloy.