Neodymiumironboron

Neodymium iron boron magnets, commonly called NdFeB magnets or rare earth magnets, are a family of permanent magnets made from an alloy of neodymium, iron, and boron. They were developed independently in the early 1980s by General Motors and Sumitomo Special Metals and have since become the strongest commercially available permanent magnets by energy density.

The dominant magnetic phase is Nd2Fe14B, a tetragonal intermetallic compound. Commercial magnets may include small amounts of dysprosium or terbium to enhance high-temperature coercivity. NdFeB magnets are produced mainly as sintered magnets or bonded magnets; they can be machined, magnetized, and formed into complex shapes.

Key properties include a high maximum energy product (BHmax) typically in the range of 30 to 50 MGOe, high remanence, and strong resistance to demagnetization when properly processed. However, they are prone to corrosion and lose magnetization at elevated temperatures, so many grades are coated and used with temperature-compensation strategies. Standard grades are used up to roughly 80–150°C, while specialized high-temperature grades can operate at higher temperatures with corresponding reductions in performance.

Manufacturing methods: sintered NdFeB magnets are made by powder metallurgy, producing dense magnets with high strength; bonded NdFeB magnets are made by mixing NdFeB powder with binders and are more flexible but weaker. Common coatings include nickel, epoxy, zinc, or multi-layer coatings to resist corrosion.

Applications include electronics, motors in hard disk drives, headphones and speakers, brushless DC motors in power tools, automotive applications and wind turbines. Due to the reliance on rare earth elements, supply, price volatility, and recycling are industry considerations.