High Induction, Low Loss FeCo-Based Nanocomposite Alloys With Reduced Metalloid Content

We present a comparative study of reductions in metalloid and early transition metal content aimed at increasing inductions in FeCo-based nanocomposite alloys. Metalloid B and early transition metal Nb glass formers were replaced with magnetic late transition metals to determine the limits of amorphous and nanocrystalline formation and increase the magnetic flux density. Alloys of composition (Fe
₆₅
Co
₃₅
)
_80+x+y
B
_13-x
Nb
_4-y
Si
₂
Cu
₁
(x=0-3, y=0,3) were cast by melt-spinning 50g batches into 2.5 mm wide, 30 μm thick ribbons. Ribbons were nanocrystallized and screened for their magnetic flux densities. The highest magnetic flux density of 1.85 T for quality ribbon was realized for the alloy with x=1, y=3. Magnetization as a function of temperature is reported for amorphous alloys to illustrate the effects of metalloid and early transition metal content on high temperature stability of magnetic properties and crystallization temperatures. Notable alloys were also synthesized by planar flow casting into 2.54 cm wide, 20 μ m ribbons and annealed under a 2.0 T transverse magnetic field. AC magnetic property measurements include permeability, coercive field, and core loss. The x=3, y=0 alloy demonstrated low core loss of 5.1 W/kg under a 0.2 T field and 20 kHz frequency with a high flux density of 1.70 T.