Influence of V and Cr Substitutions on Magnetic Properties of FeCoNbB Hitperms

Abstract

FeCoNbB Hitperm, where 4 at% of Fe are substituted by V or Cr show expected reduction of saturation, slightly lowered magnetostriction and slightly higher coercivity. Despite of significantly larger grain caused by Cr, the coercivity does not increase sharply. Detrimental ambient influences at non-vacuum annealing are not appreciably blocked by V or Cr.

Effects of air annealing on Fe–Si–B–M–Cu (M=Nb, Mo) alloys

“…Jen and Lee found that oxygen enhanced crystallization of Fe 78 Si 9 B 13 in isothermal treatments [23]. Moreover, Butvinova et al [20] reported that air promotes surface crystallization in Fe-Si-B-Nb-Cu alloys. Our samples exhibited a smaller enthalpy of Fe-Si crystallization in air than in Ar annealing (Fig.…”

“…The lower magnetic permeability of the air-annealed samples, compared to the vacuum-annealed ones, indicates that oxidation increased the magnetic hardness of the material. Butvinova et al [18][19][20] suggested why Fe-Si-B-Nb-Cu ribbons become magnetically harder with surface oxidation. On the one hand, Fe oxides are magnetically harder than Finemet.…”