The magnet sheets I cut out the use on the bottom of some tabletop miniatures sat in a sunbeam and the heat was enough to demagnetize them. So now I have to remove the magnet part that’s been super glued on, replace them, and keep them out of the sun. The magnets are to keep them stuck to a ferrous tray in a storage case.
Ferromagnetism (permanent magnetism in iron and iron alloys) happens when iron atoms (that are small magnets themselves) align to sum their magnetic fields and form a strong one we can experience in the macroscopic world.
When the magnet is heated, atoms are more energetic and more free to move around, they misalign because each atom is repelled by the others (equal poles repel each other, so when aligned they are in a constant state of repulsion, but if the material is cold they are “locked in”) and the magnetic field disappears.
There’s still atom-to-arom repulsion because of electron shells (that are negatovely charged) and attraction because of electron pairs forming a crystal bond, and other factors I don’t know about.
My explaination is a gross oversimplification, and crystal chemistry is hard, but it should give a hint of what is going on.
The magnet sheets I cut out the use on the bottom of some tabletop miniatures sat in a sunbeam and the heat was enough to demagnetize them. So now I have to remove the magnet part that’s been super glued on, replace them, and keep them out of the sun. The magnets are to keep them stuck to a ferrous tray in a storage case.
Interesting. I had no idea that UV rays demagnetize magnets.
It’s the heat, not the UV: https://en.wikipedia.org/wiki/Curie_temperature
Ferromagnetism (permanent magnetism in iron and iron alloys) happens when iron atoms (that are small magnets themselves) align to sum their magnetic fields and form a strong one we can experience in the macroscopic world.
When the magnet is heated, atoms are more energetic and more free to move around, they misalign because each atom is repelled by the others (equal poles repel each other, so when aligned they are in a constant state of repulsion, but if the material is cold they are “locked in”) and the magnetic field disappears.
I’m not sure this is true. When aligned, aren’t all the domains lined up north to south, which would be a state of attraction?
There’s still atom-to-arom repulsion because of electron shells (that are negatovely charged) and attraction because of electron pairs forming a crystal bond, and other factors I don’t know about.
My explaination is a gross oversimplification, and crystal chemistry is hard, but it should give a hint of what is going on.
Thank you for the explanation!
I think it’s just the heat itself. Seems to be what a lot of magnet sites say like https://jdamagnet.com/demagnetization-of-permanent-magnet/
Could you use a magnetizer instead of removing and replacing the metal?
Maybe! I’ll have to check into how it all works.
LOL, learned the same trying to solder magnets. Yeah, turns out heat death is a thing.