Most Production routes of Nd-Fe-B permanent magnets

A vital information about the most used production routes of Nd-Fe-B magnets has been reported. Very significant details about these routes were given, as well as manufacturing procedure of Nd15Fe77B8 and near compositions permanent magnet. Seven methods of production have been summarized, starting with the conventional powder metallurgy route and ending by the Hydrogen Decrepitation (HD) route, as they are the most applicable routes in this field. The advantages and disadvantages of the reported routes were mentioned. In fact, the HD method was found to have the following advantages in the production of Nd-Fe-B magnets: simplicity, reducing the sintering temperature, and improving the coercivity of the formed magnets. Two designed units related with the HD route has been drawn. Furthermore, some microstructures of SEM images of decrepitated polished surfaces were given to show the advantage of using the HD route in the production process of Nd-Fe-B.