High-energy-product rapidly solidified Fe–Nd–B alloys with additions of Nb and Si

Abstract

The ternary Fe82.4Nd13.1B4.5 alloy, which exhibits enhanced remanence (0.92 T) in the rapidly solidified state, was further modified by partial substitution of Nb or Si, or both Nb and Si, for Fe. The latter alloys containing Nb and Si, while maintaining remanence and coercivity values comparable with those obtained for ternary and quaternary compositions, exhibit higher (BH)max of ∼150 kJ m−3. This results from improved squareness of the demagnetization curve in the second quadrant of the B-H loop and is due to a more homogeneous distribution of very small (∼20–30 nm) crystallites through the ribbon thickness. This can be attributed to the effect of increased undercooling of the liquid alloys containing Nb and Si on quenching.