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Magnetic interactions in NdFeB bulk permanent magnets with additions

H. CHIRIAC1, N. LUPU1,* , C. CHIRIAC2, M. VALEANU3, V. KUNCSER3

Affiliation

  1. National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050 Iasi, Romania
  2. echnical University "Gh. Asachi", 49 Mangeron Boulevard, 700050 Iasi, Romania
  3. National Institute of Materials Physics, 105 bis Atomistilor Street, 077125 Bucharest-Magurele, Romania

Abstract

NdFeB-based bulk nanocomposite permanent magnets (with Dy and Co partially substituting Nd and Fe, respectively) with additions of Early Transition Metals (ETM = Mo, Ti, Zr, Cu, Nb, V, W), in form of rods with diameters ranging from 0.5 to 0.8 mm, have been prepared by devitrification annealing of amorphous and partly-amorphous precursors produced by injection die casting. A fully amorphous structure was obtained for rods with the diameter as large as 0.6 mm. The as-cast rod samples are magnetically soft and the magnetic hardness develops as the samples are devitrified to the optimum nanostructure. The best-achieved hard magnetic properties have been obtained for the optimum devitrified (15 min at 630 oC) Nd3Dy1Fe66Co10B20 samples of 0.6 mm in diameter: iHc = 296 kA/m, µ0Mr = 0.86 T, Mr/Mmax = 0.65 and (BH)max = 74 kJ/m 3 . The Mössbauer spectra indicate the coexistence of 4 magnetic phases: 2:14:1, α-Fe, Fe3B and a short range ordered intermetallic Fe-B-type phase..

Keywords

NdFeB permanent magnets, Mössbauer spectroscopy, Disordered materials, Hard magnetic properties.

Submitted at: Sept. 6, 2006
Accepted at: Sept. 13, 2006

Citation

H. CHIRIAC, N. LUPU, C. CHIRIAC, M. VALEANU, V. KUNCSER, Magnetic interactions in NdFeB bulk permanent magnets with additions, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 5, pp. 1765-1769 (2006)