Rapid Annealing Optimizing Magnetic Softness and Thermal Stability of Mn-Substituted Fe-Based Nanocrystalline Alloys

Abstract

Good high-frequency magnetic softness and thermal stability are very important for the wide application of Fe-based nanocrystalline alloys. The present work reports the influence of Mn-doping and rapid annealing on the magnetic softness, nano-structure, and magnetic-microstructure of Fe76−xSi13B8Nb2Cu1Mnx (x = 0, 1, 2, 3, and 4) alloys. It was found that the Fe74Si13B8Nb2Cu1Mn2 alloy exhibits a superior magnetic softness with the high-saturation magnetic induction of 1.32 T and a large permeability at 100 kHz of over 15,000 at a large annealing-temperature region of 120 °C. The microstructure and magnetic domains characterization indicate that the good magnetic softness and thermal stabilization can be ascribed to the superb nano-structural stability caused by the Mn doping and rapid annealing at elongated temperatures, which can maintain a fine and high number density α-Fe(Si) nano-grains and facilitate the formation of regular and wide domains.

Structural and Magnetic Properties of P Microalloyed Fe76Cu0.8Nb2.2B9Si12 Alloys

“…In addition, the annealing time can be over 60 min in the optimal temperature range of 510-570 °C, indicating the good annealing process window of the alloys. Compared with the previously reported Fe76Cu1Nb2B8Si13 [10,32], Fe76-xCu1Nb2B8Si13Mnx [33], Fe76Cu1Nb2B7Si13P1 and Fe76Cu1Nb1.5B8Si13Mo0.5 alloys [21], the present Fe76Cu0.8Nb2.2B8Si12P1 alloy has better annealing processability and superior overall magnetic properties. more than 3000.…”

“…Nevertheless, the ΔT of B8Si12P1 is still larger than that of typical Finemet alloys (140 °C) [35], and recently developed Fe73Cu1Nb2B8Si13Mn3 (149 °C) [33], Fe76Cu1Nb2B7Si13P1 (152 °C) and Fe76Cu1Nb1.5B8Si13Mo0.5 (151 °C) alloys [21], implying the good annealing process window of the present alloys. All ribbons have two distinct exothermic peaks, and the first and second crystallization peaks represent the precipitation of α-Fe(Si) and Fe-boride phases, respectively [21,33]. The difference between the first and second onset crystallization temperatures (∆T = T x2 − T x1 ) of the B 9 Si 12 ribbon is as high as 207 • C, which is much greater than that of the previously developed Fe 76 Cu 1 Nb 2 B 8 Si 13 (163 • C) alloy [10].…”

“…[10,32], Fe76-xCu1Nb2B8Si13Mnx [33], Fe76Cu1Nb2B7Si13P1 and Fe76Cu1Nb1.5B8Si13Mo0.5 alloys [21], the present Fe76Cu0.8Nb2.2B8Si12P1 alloy has better annealing processability and superior overall magnetic properties. Figure 5 shows typical hysteresis loops of the B 9 Si 12 , B 8 Si 12 P 1 and B 9 Si 11 P 1 ribbons after annealing at 550 • C for 60 min.…”

“…However, the low µ limits its application. It was found that the addition of Mn effectively enhances the high-frequency permeability of the alloy, but reduces B s , and requires a harsh rapid heating annealing process [33]. In addition, P microalloying also improves the µ of the alloy.…”

Magnetic properties evolution and crystallization behaviour of vacuum- and air-long-term-annealed rapidly quenched Fe80.3Co5Cu0.7B14 alloy

“…Lastly, many improvements in magnetic performances have been achieved by the rapid annealing process (with the heating rate of up to 1000 K/s, while standard annealing is conducted with the heating rate of 10 K/min with subsequent isothermal annealing in tenths of minutes). It has been found as an effective strategy for reducing coercivity (Hc) and core power losses (Ps) in the high-Bs alloys 10 – 12 . However, some Fe-based alloys have achieved optimal magnetic performance at the early stage of the crystallization process 13 , where initial α-Fe nanoclusters start to form.…”