RECENT DEVELOPMENTS IN THE HDDR PROCESSING OF Nd-Fe-B MAGNETS

摘要

Permanent magnets are now essential components in many fields of technology, because of their ability to provide a magnetic flux. There are two, well- established techniques for the manufacture of Nd-Fe-B permanent magnets: powder metallurgy is used to obtain high performance, anisotropic, fully dense magnet bodies; and melt-spinning is widely used to produce magnet powders for isotropic bonded magnets. A more recent technique is the Hydrogenation. Disproportionation, Desorption, and Recombination (HDDR) process, in which cast magnet alloys undergo a series of heat treatments in hydrogen and under vacuum. HDDR has proved to be an effective and economic way of obtaining powders for use in the production of high performance, anisotropic bonded magnets. In this paper, we review the history of the HDDR process, and then go on to discuss recent improvements in the processing conditions used for the production of anisotropic Nd-Fe-B HDDR powders.