Making a sintered NdFeB magnet is a bit like baking a cake: the recipe matters as much as the oven. Each ingredient has a specific job, and knowing those jobs explains why some magnets are stronger — or pricier — than others.
The main ingredients
Neodymium — the star. Neodymium is the main driver of magnetic strength; it is what makes the magnet magnetic at all. In practice it is bought as PrNd, a mix of praseodymium and neodymium — praseodymium does the same job at a lower cost.
Iron — the bulk. Iron makes up roughly two-thirds of the alloy. Think of it as the flour in the recipe: it fills the volume, but it needs the other ingredients to become a magnet.
Boron — the glue. Boron is only about one percent of the mix, yet it is essential: without it the main magnetic phase cannot form at all. A tiny amount that holds everything together.
The heat-resistant helpers
Dysprosium and terbium are the expensive additions. They help the magnet hold its strength at high temperatures, which is why high-temperature grades (SH, UH, EH) contain them. The hotter the application, the more dysprosium goes in.
Small additions — tiny amounts of cobalt, copper and aluminum — improve corrosion resistance and strengthen the grain boundaries. Oxygen and carbon are the enemy: even a little quietly weakens performance, so the process stays protected from air.
At a glance
| Element | Job in the magnet |
|---|---|
| Nd (as PrNd) | Main driver of magnetic strength |
| Fe | Fills the volume, provides the magnetic moment |
| B | Holds the magnetic phase together — essential at ~1% |
| Dy, Tb | Add heat resistance for hot applications |
| Co, Cu, Al | Fine-tune corrosion resistance and strength |
| O, C | Impurities — kept out to protect performance |
The exact recipe is every maker's secret — the roles above are the same everywhere.
Read on: melting and strip casting → · the whole production flow →