Increased induction in FeCo-based nanocomposite materials with reduced early transition metal growth inhibitors

Abstract

We report on new high-saturation induction, high-temperature nanocomposite alloys with reduced glass formers. The amounts of the magnetic transition metals and early transition metal growth inhibitors were systematically varied to determine trade-offs between higher inductions and fine microstructures with consequently lower magnetic losses. Alloys of nominal composition ͑Fe 65 Co 35 ͒ 79.5+x Nb 4−x B 13 Si 2 Cu 1.5 ͑x=0-4͒ were cast into a 28 mm wide, 20 m thick ribbon from which toroidal cores were wound. Inductions and magnetic losses were measured after nanocrystallization and stress relief. We report technical magnetic properties: permeability, maximum induction, remanence ratio, coercive field, and high frequency magnetic losses as a function of composition and annealing temperature for these alloys. Of note is the development of maximum inductions in excess of 1.76 T in cores made of alloys with the x = 4 composition and maximum inductions in excess of 1.67 T in alloys with the x = 3 composition, which also exhibit power losses smaller than 10 W/kg at 0.2 T induction levels in 20 kHz fields. We discuss optimization of induction with chemistry and correlate the microstructures with losses.

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

“…Nanocomposite alloys (HTX002-type [1][2][3] ) of composition (Fe 65 Co 35 ) 79.5þx B 13 Nb 4Àx Si 2 Cu 1.5 (x ¼ 0-4) and (Fe 65 Co 35 ) 83 B 10 Nb 4 Si 2 Cu 1 , designated alloy "10-4", were studied to determine the kinetics of and phase evolution in secondary crystallization. HTX002 nanocomposites exhibit high saturation flux densities up to 1.85 T and low losses at kHz level frequencies, [1][2][3] making them promising for inductive components in high frequency power electronic applications. The formation of crystalline phases other than a-FeCo deteriorate these properties.…”

Mass Balance and Atom Probe Tomography Characterization of Soft Magnetic (Fe₆₅Co₆₅)_79.5B₁₃Si₂Nb₄Cu_1.5 Nanocomposites

“…The quantified correlation of local composition with nanostructure done here is applicable to previous qualitative reports [8], [11]. Moreover, the models developed, techniques used, and the overall trends presented here are applicable to the whole range of magnetic nanocomposite materials.…”

“…Samples designated HTX002 developed to maximize saturation induction, of composition (Fe 65 Co 35 ) 79.5 B 13 Si 2 Nb 4 Cu 1.5 , were synthesized [8], [11], [20]. The alloy exhibits relative permeability >1200, saturation induction of 1.76 T, and power loss of 10 W/g at 0.2 T and 20 kHz.…”

“…Heat treatment at temperatures above the primary crystallization temperature, T x1 , partially devitrifies an amorphous precursor, resulting in nanocrystalline/amorphous composite material [1], [7]. Manuscript Magnetic TL elements {Fe, Co, Ni} that are rich in the crystal phase are the majority constituent and are the root of both phases' magnetic induction [7], [8]. Glass-former (GF) elements include both small atom metalloids (B, Si, Ti, etc.)…”

Crystallization behavior and high temperature magnetic phase transitions of Nb-substituted FeCoSiBCu nanocomposites

“…3,[8][9][10][11] In prior research, we have observed the crystallite size to become finer with the addition of Nb, resulting in the development of materials with a low core loss. 12 The nanocrystallization process of HITPERM alloys is quite different than that of FINEMET alloys. 13 It is reported that Cu clustering is strongly reduced in FINEMET alloys by the substitution of Fe by Co, 14 although in other Co-rich alloys the density of Cu clusters is insufficient to explain the copious nucleation in these alloys.…”