Developing Bonded HDDR Magnets for a Slovenian SME

Abstract

As part of a NATO Science-for-Peace industry-based project we studied the effects of Pr and Zr substitutions to a basic Nd₁₅DyFe₇₆B₈ alloy in order to develop a material and a process which could be easily transferred to factory production. We processed the materials using a conventional hydrogenation-disproportionation-desorption-recombination (HDDR) process and a simple rotary-pump-type vacuum. 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 Nd, and for Zr a much smaller 0.1 atomic % 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 optimising 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.