The Hydrogen Ductilisation Process (HyDP) for shaping NdFeB magnets

One of the major drawbacks of NdFeB-based, fully dense, sintered magnets is that they are hard and extremely brittle. Therefore, in order to produce the final shape and precise dimensions, they often have to be ground and this process is time consuming, energy intensive and produces a significant amount of waste material which is not readily recyclable. This paper reports a potentially new and exciting application of hydrogen as a promising processing tool in which the normally brittle Nd2Fe14B based intermetallic could be compressed at room temperature in a ductile, disproportionated condition and then restored to its original state by the removal of the hydrogen under partial vacuum at elevated temperatures. Under appropriate conditions, this stage can also produce a useful degree of anisotropy. This paper describes the salient feature of this process which has been called the Hydrogen Ductilisation Process (HyDP) and describes possible applications of the HyDP in the production of NdFeB-type permanent magnets.