Secondary crystallization in (Fe65Co35)79.5+xB13Nb4−xSi2Cu1.5 and (Fe65Co35)83B10Nb4Si2Cu1 nanocomposite alloys

Here, secondary crystallization kinetics of high induction, low loss HTX002-type nanocompositealloys with the compositions (Fe₆₅Co₃₅)_79.5+xB₁₃Nb_4−xSi₂Cu_1.5 (x = 0-4) and (Fe₆₅Co₃₅)₈₃B₁₀Nb₄Si₂Cu₁ are reported. The magnetization of the alloys was measured through the thermal cycle of 50 °C-700 °C-300 °C-800 °C-300 °C-900 °C-200 °C by vibrating sample magnetometry. In (Fe₆₅Co₃₅)_79.5+xB₁₃Nb_4−xSi₂Cu_1.5alloys, the stability of the (Fe,Co,Nb)₂₃B₆ (23-6) phase is increased with increasing Nb content. In the x = 4 alloy, (Fe,Nb)₂B is the only secondary crystalline phase to form, demonstrating that Nb is necessary for the 23-6 phase to form. The (Fe₆₅Co₃₅)₈₃B₁₀Nb₄Si₂Cu₁alloy forms the 23-6 phase more readily than the x = 0 alloy, likely due to the lower B content. The kinetics of secondary crystallization are important to assess long-term ageing effects on the metastable microstructure at elevated temperatures.