Neodymium Magnets, Sample 4: 81Fe-4B-15Nd Sintered (Sagawa 1988)

Neodymium magnets are iron, boron and neodymium. Sagawa's team at Sumitomo melted the three together, ground the casting to a powder finer than 10 µm, lined the grains up in a magnetic field while pressing them, and sintered the compact in argon. This is their sample 4, 81 % iron, 4 % boron and 15 % neodymium by atoms: 13.4 MGOe. Source: M. Sagawa et al. (Sumitomo Special Metals), US 4,770,723 (1988). Unknown: how the pure iron, the ferroboron and the neodymium metal are made, and how the finished magnets are magnetised; the patent does not say. The 1 kg weights are our arithmetic from the patent's atomic percentages. Picture: the patent's Fig. 8.