Preparation and magnetic properties of Bi-doped NdFeB-based melt-spun nanocrystalline ribbons

Abstract High spontaneous magnetization ( M sp ) and large magneto-crystalline anisotropy energy ( K u ) make NdFeB-based alloys and permanent magnets prepared thereof, remain the ace of the world magnet market. The search for novel approaches for the mass production of high-performance NdFeB-based melt-spun ribbons continues in order to create new opportunities for manufacturing high performance bonded magnets. This paper deals with the effects of Bismuth (Bi) doped into the mother phase of slightly enriched soft phase Fe modified a little by Co, Nd 2 (Fe 0.93 Co 0.07 ) 15 B. The Bi-doping was performed by using the pseudo-eutectic phase of Nd 92 Bi 8 . This doping helps reduce the grain size, enhance the texture degree and reinforce the crystal growth along the ribbons’ surface and improves the magnetic performance of doped NdFeB-based ribbons. The present energy product (BH) max of this kind of ribbons is around 20 MGOe. The route of production and impacts of dopant on the phase, microstructure and magnetic properties were investigated in details.