Sintered NdFeB magnets

The development of sintered NdFeB magnets delivered the strongest magnet materials with the highest room-temperature magnetic field (remanence) and demagnetisation resistance (coercivity). The associated success story includes numerous applications with higher efficiencies due to higher power density and even applications that could only be enabled through the use of NdFeB. The biggest applications in terms of demand are wind turbine generators and traction machines for automotive. Traction machines contain one to three kilograms of sintered NdFeB, and wind turbine generators contain more than 1,000kg of this material.

Sintered NdFeB magnets derive their coercivity and resulting temperature stability from the use of heavy rare earth elements, such as dysprosium, terbium, and holmium. The increasing demand for high-temperature stable magnets, driven by the electrification of automobiles, has resulted in price increases for these elements. The entire magnet industry is searching for processes to reduce these elements while maintaining or even improving the temperature stability. The first sintered NdFeB magnets using heavy rare earths were produced by what is now referred to as the traditional method: 600-1,200kg of heavy-rare-earth-containing material was melted, pulverised, pressed, aligned, and sintered. Afterward, the produced magnet material was cut into final dimensions.

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