I need to ask a few questions, please help??

[Ein_Wannabe]

Hey guys thanks for reading.
Usually I would float on down to the local University, however due to newly imposed campus laws only students are permitted.

To start with, classic rookie question, when a metal (Let's say Iron for example) is in its liquid/molten form, does it react to magnetism the same as it would as a solid?

And if not, are there any metals that do?

(Tried googling a lot of the questions I have to no avail)

Cheers again!!

[swansont]

Hey guys thanks for reading.

Usually I would float on down to the local University, however due to newly imposed campus laws only students are permitted.

 

To start with, classic rookie question, when a metal (Let's say Iron for example) is in its liquid/molten form, does it react to magnetism the same as it would as a solid?

 

And if not, are there any metals that do?

 

(Tried googling a lot of the questions I have to no avail)

 

Cheers again!!

 

No, they don't. Ferromagnetic materials rely on the crystal structure of the solid to form domains that all have the same orientation, in order to give a net magnetism to the material. When it drops below the Curie point, that magnetism is lost. The melting point is higher than the Curie point (for all ferromagnetic materials, AFAIK)

 

So-called ferrofluids have a colloidal suspension of ferromagnetic materials, but generally do not retain the magnetism in the absence of an external field, so they are really acting as a paramagnetic substance.

 

 

Paramagnetic and diamagnetic materials might react in similar ways, depending on their structure when solid. They might react more strongly, as they are all free to orient themselves and be attracted or repulsed by the field, while as a solid they can't.

[Ein_Wannabe]

So just to check that I'm understanding this correctly, if a Ferrofluid is subject to a constant external electromagnetic field, it will retain it's magnetism and react accordingly to the external field?

Also possibly along with Paramagnetic and Diamagnetic materials?

Thanks for the quick reply too!!

[swansont]

A ferrofluid only has its shape if there is an external field. Para- and diamagnetism are generally much weaker.

[Enthalpy]

I know no material that stays ferromagnetic beyond its melting point. But would it be possible? Unclear to me.

 

Liquids show some order, but only at a small scale, and this scale reduces quickly as temperature rises a little over the melting point. Liquid crystals keep order to a longer range and over a wider temperature span. This might open the possibility, maybe perhaps.

 

It seems that nobody has found a ferromagnetic liquid up to now, since technology reverts to ferrofluids instead, despite their drawbacks.

 

A ferromagnetic liquid would be very nice to build fridges.