Magnetic properties of ultrasoft-nanocomposite FeAlSiBNbCu alloys

The effects of up to 10 at% substitution of Fe by Al on the microstructure and DC and AC magnetic properties of nanocrystalline FeSiBCuNb alloy ribbon are summarised and analysed. The minimum DC H-c developed during annealing decreases by 40% for 2 at% Al (to 0.3 A/m) and remains roughly constant fo r larger Al contents. The largest peak value of mu(0.4) at 50 Hz also corre sponds to 2 at% Al. The best frequency response for mu(0.4) occurs for 6 at % Al while there was no improvement in AC power loss behaviour over the 0% Al alloy. The improvements in DC H-c and AC mu(0.4) are ascribed to a reduc tion in K-1 of the Fe-Si-based nanocrystallites by the introduction of Al. (C) 2000 Published by Elsevier Science B.V. All rights reserved.