Temperature Effects on Permanent Magnets: Exploring Neodymium Magnet Performance

[Woodski]

I am interested in the effects of temperature on Permanent Magnets. I understand that Neodymium magnets lose -0.09 ~ -0.13% of Br/°C and can work stably under 80°C for low Hci Neodymium magnets.
However, what happens to them just over this 80°C limit? Do they still have some magnetic strength to attract and repel? If they are cooled, do they retain their full strength or do they loss some strength?

 

[ranger]

Usually the manufacturer will provide a graph, with a BH Curve. Example: http://www.mceproducts.com/_img/materials/N3571.pdf

The Temperature coefficient of Br is a property that describes how the magnetic property changes with temperature. This change is reversible though - the magnetic property returns when the temperature is returned to its original operational point.
But if you don't exceed the knee (shown on the graph), the changes in magnetic property are reversible, otherwise, in most cases it is not.

You will also need to keep in mind something called the curie temperature (Tc). If you exceed this temp, the ferromagnetic material completely loses its magnetic property (and changes in most cases are irreversible).

 

[astrokreng]

I can confirm that temperature does indeed have an effect on the performance of permanent magnets, particularly Neodymium magnets. The decrease in magnetic strength with increasing temperature is due to a decrease in the magnet's intrinsic coercivity (Hci) and remanence (Br). This is known as the Curie temperature, which is the temperature at which the magnetic properties of a material change.

In the case of Neodymium magnets, they lose approximately 0.09-0.13% of their Br per degree Celsius above 80°C. This means that at temperatures just above 80°C, the magnet's magnetic strength will decrease, but it will still have some ability to attract and repel. The exact strength will depend on the temperature and the specific properties of the magnet.

If the magnet is cooled back down to lower temperatures, it will regain some of its lost strength. However, it is important to note that permanent magnets are not completely reversible. This means that they may not regain their full strength even after being cooled back down. The extent of this loss will depend on the specific properties of the magnet and the temperature it was exposed to.

In summary, Neodymium magnets can still work at temperatures just above 80°C, but their magnetic strength will decrease. If they are cooled back down, they will regain some of their strength, but it may not be at the same level as before. It is important to carefully consider the temperature limitations of permanent magnets when using them in applications to ensure optimal performance. Further research and experimentation may be needed to fully understand the effects of temperature on permanent magnets.