Rare-Earth-Iron-Boron permanent magnets by rapid solidification processing

Abstract

The development of a light-rare-earth-iron-based permanent magnet has been a long standing goal of the permanent magnet industry. The first successful attempts at magnetically hardening these materials employed rapid solidification techniques. This work culminated in the discovery of the NdFeB-based permanent magnet materials, the properties of which have been shown to derive from the Nd₂Fe₁₄B intermetallic phase. This class of magnets has received considerable scientific and commercial interest stemming from the fact that energy products already significantly exceed those of the SmCo-based materials. Moreover, owing to the relative abundance of neodymium, the cost of these materials is potentially much lower.

Processing these magnets is carried out by two distinctly different techniques. These include the conventional powder metal-sinter process and consolidation of rapidly solidified materials. This paper discusses the preparation of these materials by the latter method. Included are the properties of the rapidly solidified ribbons themselves, methods for consolidating these materials into monolithic magnet shapes, microstructural data, and long-term thermal aging characteristics.