Influence of Al addition on structural, crystallization and soft magnetic properties of DC Joule annealed FeCo based nanocrystalline alloys

The effect of minor Al addition on structural, crystallization, soft magnetic behaviour and magnetic field induced anisotropy through DC Joule annealing in (Fe53.95Co29.05)(83)Si1.3B11.7-xNb3Cu1Alx, (X = 0, 1) alloys has been studied. The Al added as-quenched melt spun ribbons show good glass forming ability, better thermo-physical properties like a high T-x1 of 438 degrees C, Tc-am of 435 degrees C and Tc-nc of 906 degrees C, compared to T-x1 of 389 degrees C, Tc-am of 409 degrees C and Tc-nc of 900 degrees C for the alloy without Al addition. The longitudinal magnetic field annealed Al added alloy exhibits low Hc of 12.92 A/m and maximum Ms. of 1.78 T. The better soft magnetic properties of Al added alloy are achieved through a high nucleation density of BCC-FeCo(Al) nanocrystallites having low K-1 and lambda values. The as-quenched alloys possess high magneto-strain exceeding 30 ppm and approach near zero value on nanocrystallization. The longitudinal magnetic field assisted DC Joule annealing, having current density (J) in the range of J = 20-25 A/mm(2) promotes good magnetic softening due to precipitation of 5-35 nm nanocrystallites as explained by extended-random anisotropy model. The Al added alloy shows better magnetic field induced anisotropy (K-u) on nanocrystallization and shows visible change in the shape of hysteresis loop. (C) 2017 Elsevier B.V. All rights reserved.