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Q & A: heated ferromagnet re-magnetized

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Most recent answer: 02/18/2020
Q:
Hello, I baked a NdFeB magnet around 300 C for about 12 hours, while it's curie temperature is 340 C. I found the NdFeB magnet is almost demagnetized. later we remagnetize the magnet to saturation level by external pulse magnetizing fixture. Can the remagnetized NdFeB have the same performances (Br, and thermal coefficient of Br), and reliability (Hcj,and thermal coefficient of Hcj, capability against demagnetization)? or in other word, Can the re-magnetized NdFeB perform as as same as virgin NdFeB?
- YONG LI (age 35)
Claremore,OK,USA
A:

I'm not 100% sure, because there could have been some diffusion of atoms changing the crystal structure a bit. Nevertheless, the main process you'd expect to happen at 300°C would be to free up domain wall motion allowing demagnetzation, which lowers the magnetc potential energy. That process would be reversable by your remagnetization.

So my best guess is that it would be pretty close to initial specs, but assuming that the original structure was optimized, it's likely to fall a little short.

Mike W.


(published on 02/18/2020)

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