Fe(Co)SiBPCCu nanocrystalline alloys with high B_s above 1.83 T

Highlights: • Fe(Co)SiBPCCu nanocrystalline alloys were successfully developed. • The FeSiBPCCu alloy exhibits high B_s of 1.83 T and low H_c of 5.4 A/m. • Excessive substitution of Co for Fe drastically deteriorates magnetic properties. • The FeSiBPCCu alloy exhibits good frequency properties and temperature stability. • The excellent properties stem from the uniform microstructure and wide domains. - Abstract: Fe_84.75-xCo_xSi₂B₉P₃C_0.5Cu_0.75 (x = 0, 2.5 and 10) nanocrystalline alloys with excellent magnetic properties were successfully developed. The fully amorphous alloy ribbons exhibit wide temperature interval of 145–156 °C between the two crystallization events. It is found that the excessive substitution of Co for Fe greatly deteriorates the magnetic properties due to the non-uniform microstructure with coarse grains. The alloys with x = 0 and 2.5 exhibit high saturation magnetization (above 1.83 T), low core loss and relatively low coercivity (below 5.4 A/m) after annealing. In addition, the Fe_84.75Si₂B₉P₃C_0.5Cu_0.75 nanocrystalline alloy also exhibits good frequency properties and temperature stability. The excellent magnetic properties were explained by the uniform microstructure with small grain size and the wide magnetic domains of the alloy. Low raw material cost, good manufacturability and excellent magnetic properties will make these nanocrystalline alloys prospective candidates for transformer and motor cores.