The Development of Microstructure during HDDR Treatment of Sintered NdFeB-type Magnets

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Colleges, School and Institutes


The hydrogen absorption and desorption characteristics of the hydrogenation disproportionation desorption and recombination (HDDR) process on scrap sintered neodymium-iron-boron (NdFeB) type magnets has been investigated. The microstructural changes at each stage of the process have been studied using high resolution scanning electron microscopy (HR-SEM). These studies indicate that the hydrogenation of the grain boundaries and triple junctions during disproportionation may have been affected by the high oxygen content of the sintered NdFeB magnets in particular, some oxidised triple junctions appear to remain unreacted throughout the entire HDDR reaction and hence remain in the fine recombined microstructure.


Original languageEnglish
Title of host publicationProceedings of the 23rd International Workshop on Rare Earth Permanent Magnets and their Applications
Publication statusPublished - Aug 2014