New non-magnetostrictive metallic glass

A new metallic glass, (METGLAS
^®
alloy) Co
74
Fe
6
B
20
, has been identified which exhibits ∼ zero magnetostriction (
|\lambda_{s}|<0.4\times10^{-6}
). The saturation induction of this new alloy, 11.8 kG, is approximately twice that reported for other non-magnetostrictive glasses with similar transition-metal (TM) content but including the metalloids P and Al or Si in addition to B. This larger magnetization results from the weaker hybridization of the TM d-bands with the valence bands of boron than with those of other metalloids. Due to the absence of magnetostriction, no coupling between winding stresses and magnetic properties exists. Hence, as-quenched/as-wound toroids of Co
74
Fe
6
B
20
glass exhibit exceptional low-field magnetic properties:
H_{c} = 0.035
Oe,
B_{r} = 9800
gauss and
\mu_{max} = 280,000
.