Effect of P microalloying on magnetic properties and structure of FeSiBNbCu nanocrystalline alloy

Phosphorus (P) is a cheap and effective element that inhibits grain growth and improves soft magnetic properties in Fe-based nanocrystalline alloys. However, most alloys usually require high P content, leading to problems such as volatilization and oxidation during production process. In this paper, we study and report new findings regarding the effect of P microalloying on the magnetic properties, microstructure and magnetic domain structure of Fe 77.8 Si 10 B 9− x Cu 0.6 Nb 2.6 P x ( x = 0 and 1) nanocrystalline alloys. The substitution of B by 1 at% P has little influence on the crystallization behavior, saturation magnetic flux density ( B s ) and permeability ( μ ) of the alloy, while effectively reduces the coercivity ( H c ) in a wide annealing temperature range. The reduced H c can be attributed to the low magnetocrystalline anisotropy and wide magnetic domains caused by uniform and fine α-Fe(Si) grains. The mechanism of structural evolution induced by 1 at% P is also been discussed. The P microalloyed nanocrystalline alloy with high B s of 1.43 T, high μ up to 27,000 at 1 kHz, and low H c of 1.4 A/m is suitable for magnetic shielding piece of wireless charging.