Rare earth metals, such as metallic neodymium and metallic didymium (metallic praseodymium-neodymium), are used for rare earth magnets, mainly neodymium-iron-boron magnet.

稀土，钕和皮（镨，钕） ，用于稀土磁，主要钕硼磁。

Evolving process of hub dynamo which used in bicycle is presented. The performance of magnetite viz. ferrimagnetism or NdFeB is analyzed. The prospect of marketing is viewed.

摘要介绍了自行车上使用的花鼓式发电机的演变，析了所用磁石，即氧体或钕硼的性能优劣，并进行了市场前景展望。