The Preparation of Neodymium-Metal and NdFeB-Alloys

Abstract

The various possible methods of processing neodymium-metal by metallothermic reduction of neodymium-alloys were theoretically investigated. Thermodynamiccal culations as well as reflections on feasibility lead to the conclusion that calciothermic reduction of neodymium fluoride presents an ideal solution to the problem. Based upon the theoretical investigations a process for production of neodymium-metal was worked out and developed up to a technical scale.

In parallel various possible methods of production of NdFeB-based magnetic alloys were tested. The theoretical investigations pointed towards advantages of the Vacuum-Induction-Melting-Process (VIM). Based up on this process a technical scale production process was worked out and the parameters for crucible material, cooling rate, superheating/pouring temperature and the control of impurities optimised. The process was developed up to a commercial scale.

Within the frame work of the CEAM-cooperation a process for technical production of NdFeB-hydrides was developed. The hydride is produced in a two-stage-process:

• Alloyproduction

• Hydrogenation

The results show that a controlled hydrogenation yields a hydride with contents of about 0,3–0,4% of homogeneously distributed hydrogen. The productionprocess was also developed up to a commercial scale.