Little Question about magnetization and heat

In summary, it is possible to magnetize metals with heat by heating the metal and exerting an external magnetic field while it cools. However, exposing a metal to heat without an external magnetic field usually results in demagnetization. It is also possible for a metal to become magnetic while cooling down if it is exposed to a magnetic field during the process.
  • #1
rauven
1
0
Hello, I'm new so i hope I'm not posting this question on the wrong section, anyway, here's the question:

Is possible to magnetize metals with heat?

I'm asking because today i found out that my scissors became slightly magnetic after being in touch with fire for a while (i was using them as tweezers).

I don't remember having them near any magnets so that's why I'm curious...

thanks
 
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  • #2
Hi and welcome to PF.

Well commercial magnets are made usually heating the metal or alloy and then exerting external magnetic field while it cools so that the atoms and electrons align to create this kind of phenomenon as we call magnetism. There are other ways too like wrapping a wire around a metal and connecting the ends of the wire to a direct current source.Although this usually doesn't end up as magnetizing the metal for a long time and depends on the voltage/current used and other factors.

Magnets can demagnetize if exposed to heat because of the rupture of particle alignment in the material that was responsible for the magnetism in the first place.But to answer your question I haven't heard nor seen in my own experience that a metal being heated by any means with no external magnetic field would become magnetic. Only the other way around that metal while exposed to heat can loose it's magnetic abilities.

Maybe you had a coincidence that while your scissors were cooling down they experienced somekind of a magnetic field , and it doesn't always have to be a permanent magnet like the one from a fridge sticker or speaker as you would think it could be some electrical wires or equipment.
Although most electrical wiring in house uses the mains AC which can't induce long term magnetism because the polarity is constantly changing.
 
  • #3
Ferromagnetic materials like iron always have magnetic domains. Each domain is like a little bar magnet. But, in an unmagnetized piece, the domains are small and jumbled so their magnetizations cancel out. If you heat up a piece, it becomes easier for the domains to flip and meld, so when you cool it down again, the domains might not cancel out anymore, and it becomes magnetic. But if you do this in an uncontrolled manner, you could just end up demagnetizing the piece again.

If you expose the piece to a magnetic field when it is hot and slowly cool it off, then it should become magnetic.
 

Related to Little Question about magnetization and heat

1. How does magnetization affect heat?

Magnetization is the process of aligning magnetic dipoles in a material to create a magnetic field. This process does not directly affect heat, but it can indirectly influence it by changing the material's physical properties. For example, some materials exhibit a phenomenon called the magnetocaloric effect, where changing the material's magnetization causes a change in its temperature.

2. Can heat affect magnetization?

Yes, heat can affect magnetization through a process called thermal demagnetization. When a material is heated, its thermal energy can disrupt the alignment of magnetic dipoles, causing them to become disordered and reducing the overall magnetization of the material.

3. How does the temperature dependence of magnetization vary between different materials?

The temperature dependence of magnetization, also known as the Curie temperature, varies greatly between different materials. Some materials have a high Curie temperature, meaning they maintain their magnetization at high temperatures, while others have a low Curie temperature and lose their magnetization at relatively low temperatures.

4. What is the relationship between magnetization and entropy?

There is a direct relationship between magnetization and entropy, as increasing the magnetization of a material often leads to a decrease in entropy. This is because aligning magnetic dipoles in a material reduces the number of available microstates, leading to a decrease in entropy.

5. How is magnetization measured in a material?

Magnetization is typically measured using a device called a magnetometer, which can detect and measure the strength and direction of a material's magnetic field. Different types of magnetometers use various techniques to measure magnetization, such as Hall effect sensors, SQUIDs, and vibrating sample magnetometers.

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