Toward the reduction of Heavy Rare Earth elements in high performance NdFeB permanent magnets by the refinement of the strip cast flakes microstructure
Abstract
NdFeB alloys for permanent magnets are produced by the strip cast process which consists in melting the raw materials in an induction furnace followed by pouring the melted alloy on a copper water cooled rotating wheel. This process allows producing NdFeB flakes with the microstructure well adapted to the further process steps of the manufacturing process of high performance sintered magnet. This study provides an evidence of the correlation between the microstructure of the starting alloys after strip casting process and the coercivity increase in NdFeB PMs. The refinement of the microstructure allows the production of fine-grained magnets with significant reduction of HRE elements (up to 39%). Thereby the potential to save overall time and costs is relevant by optimizing the microstructure of the alloys during the strip-casting step in order to ensure a homogenous distribution of the grain boundary phase in NdFeB permanent magnets.