Irreversible magnetic losses for melt-spun nanocrystalline Nd/Pr-(Dy)-Fe/Co-B ribbons

The thermal stability of nanocrystalline melt-spun Nd/Pr-(Dy)-Fe/Co-B alloy ribbons, defined in terms of the long-term and short-time irreversible losses in remanence and coercivity, has been investigated. Cobalt substitution for iron improves the thermal stability of nanocrystalline (Nd/Pr)-(Fe/Co)-B alloys through reducing both long-term and short-time irreversible losses. Nanocomposite alloys manifest lower long-term irreversible losses than single phase alloys. Dysprosium substitution for (Nd/Pr) also decreases the irreversible losses. It is demonstrated that the magnitudes of the Curie temperature, coercivity, saturation magnetization and the degree of inter-crystalline exchange coupling have important effects on the irreversible losses.