Magnetic properties and structure of Nd-Fe-B melt-spun alloys for isotropic bonded magnets

Abstract

The phase evolution and magnetic properties of both melt-spun NdₓFe₉₈.₉₋ₓB₁.₁ x = 10-39 mass % ribbons and isotropic bonded magnets have been investigated. A high coercivity and remanence has been shown to be attainable even in the as-spun state with Nd in the range of x = 28-30 mass % without heat treatment. The influence of heat treatment in the 530 to 730° C range on magnetic properties of melt-spun ribbons has been studied. A well-expressed effect of Nd concentration on the lattice volume of Nd₂Fe₁₄B (P4₂/mnm) phase and volume fraction of secondary phases has been revealed. It was shown that exchange-coupling effect plays important role in the hard magnetic properties of the alloys with low Nd content, but melt-spun alloys with high remanence along are not sufficient to guarantee high magnetic performance.