Abstract
Addition of minor Mn effectively improves the amorphous-forming ability and thermal stability of the Fe85Si2B8P4Cu1 alloy. With increasing the Mn content from 0 to 3 at.%, the critical thickness for amorphous formation and onset temperature of the primary crystallization increase from 14 μm and 659 K to 27 μm and 668 K, respectively. The fine nanocrystalline structure with α-Fe grains in size (D) of < 20 nm was obtained for the annealed amorphous alloys, which show excellent soft magnetic properties. The alloying of Mn reduces the coercivity (Hc) by decreasing the D value and widens the optimum annealing temperature range for obtaining low Hc, although the saturation magnetic flux density (Bs) is decreased slightly. The Fe83Mn2Si2B8P4Cu1 nanocrystalline alloy possesses fine structure with a D of ∼17.5 nm, and exhibits a high Bs of ∼1.75 T and a low Hc of ∼5.9 A/m. The mechanism related to the alloying effects on the structure and magnetic properties was discussed in term of the crystallization activation energy.
Highlights
Fe-based Fe-Si-B-Nb-Cu nanocrystalline alloys (FINEMET) have been widely used as magnetic cores in inductors, sensors and high frequency transformers because of their high permeability, low coercivity (Hc) and low core loss in high-frequency range.[1,2,3,4] These excellent soft magnetic properties result from their unique microstructure composed of α-Fe grains in nano-size dispersing uniformly in the amorphous matrix, which can be well understood on the basis of the random anisotropy model.[5]
Fe-Mn-Si-B-P-Cu alloys, strong chemical short-range ordering could be produced in the liquid state between the atomic pairs with large negative ∆Hmix, which could retard the precipitation of crystal phases by increasing the difficulty of atomic movement, and improves the amorphous-forming ability (AFA) and thermal stability of amorphous alloys.[16,17]
It should be noticed that the alloy with x = 2 shows a high Bs of 1.75 T and a low Hc of 5.9 A/m, which suggests that 2 at.% is the optimal Mn content for magnetic properties
Summary
Fe-based Fe-Si-B-Nb-Cu nanocrystalline alloys (FINEMET) have been widely used as magnetic cores in inductors, sensors and high frequency transformers because of their high permeability, low coercivity (Hc) and low core loss in high-frequency range.[1,2,3,4] These excellent soft magnetic properties result from their unique microstructure composed of α-Fe grains in nano-size dispersing uniformly in the amorphous matrix, which can be well understood on the basis of the random anisotropy model.[5]. Adding minor Nb or Ti is an effectively way to improve the AFA of Fe-based alloys owing to their large negative enthalpies of mixing (∆Hmix) with the components in the alloys and enhance magnetic softness of Fe-based nanocrystalline alloys by refining the microstructure,[11,12,13] while deteriorates Bs of the alloys. It has been reported that the substitutions of Mn for Nb and Ti in Fe-Zr-B-Cu alloy system could increase Bs of the alloys,[14] suggesting Mn has less influence on decreasing Bs as compared with Nb and Ti. In present study, with the aim of improving the AFA and
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
