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Coercivity variations with Pr- and Zr-substituted NdDyFeB-based HDDR powders

2001; Elsevier BV; Volume: 237; Issue: 3 Linguagem: Inglês

10.1016/s0304-8853(01)00698-9

1873-4766

P.J. McGuiness, Spomenka Kobe, Irena Škulj, A. Bollero, Oliver Gutfleisch, E. Devlin, D. Niarchos,

Rare-earth and actinide compounds

As part of an industry-based project, we studied the effects of Pr and Zr substitutions to a basic Nd15DyFe76B8 material. We processed the materials using a conventional hydrogenation-disproportionation-desorption-recombination (HDDR) process and a simple rotary-pump vacuum; however, we also experimented with high-vacuum conditions in order to see what effect these had. The Pr and Zr substitutions were observed to have a positive and cost-effective influence on the coercivity of the processed powders: the optimum Pr substitution was the replacement of three-quarters of the neodymium, and for Zr, a much smaller 0.1 at% was found to be the best. Microstructural observations of the as-cast structures revealed significant differences between the Zr- and Pr-substituted materials and the additive-free NdDyFeB alloy, but post-HDDR microstructures were all very similar and provided little help for optimizing the processing conditions. By combining the substitutions of Pr and Zr in a relatively rare-earth-rich alloy, we were able to produce a coercive powder of >1000 kA/m and have a process which can now be quickly and easily transferred to the factory.