Magnets are a welcome addition to our everyday life. Its existence may often be overlooked, but it has significantly contributed to the society we have today.
The industrial and healthcare sectors have utilized the magnetic forces to elevate their services further. We can even see them in our homes if we looked hard enough. From electric fans, toys, trains, cars, and washing machines, magnets are indeed an essential part of modern living. You are even holding one in your hands right now – our gadgets also utilize the benefits of magnetic fields!
Have you ever wondered what happens to a magnet if it is heated?
Well, the short answer is that the magnet will lose its magnetic properties and won’t function the same as before.
How Much Heat Can a Magnet Withstand?
Magnets are susceptible to heat. Average magnets can only withstand heat of below 80 degrees. When these magnets are exposed to higher temperatures, the magnetic properties are compromised.
It is important to note that magnets are made of different metals; therefore, their capacity to withstand high temperatures can vary.
The 80 degrees Celsius is the threshold that can result in demagnetization or what they call the Currie point. However, some magnets can withstand the heat of 600 up to 800 degrees Celsius, depending on the type of magnet. When the magnet is heated even further, it will melt and turn into vapor, leading to a destroyed state.
Will High Heat Destroy a Magnet?
High temperatures generally make the molecules vibrate faster and cover a wide range of areas. As a result, these atoms move at a greater speed than average and take up more space, which yields in expansion. This applies to every matter, be it solid, liquid or gas.
Magnets are no exception.
Typically, the atoms align between the negative and positive poles, which results in a strong magnetic field. However, when high temperature is applied, magnetic particles actively moved at a random, fast pace.
The thermal energy disrupts the magnetic walls; both the negative and positive poles get jumbled and point in the opposite direction. These constant movements create chaos within the atoms and cause misalignments – until the magnetic properties wear off.
When the heat rises and reaches what we call the Curie temperature, another change occurs. Curie temperature is named after French physicist Pierre Curie and measures above 176 degrees Fahrenheit or around 80 degrees Celsius. This threshold has high enough heat to stop the total atomic alignment of the magnet, which contributes to the destroyed magnetic domains.
This will result in a permanent demagnetization.
It is best to remember that magnets are made of different metals, so their Curie temperatures vary from each other. Typically, magnets have an average Curie temperature from 60 to 80 degrees Celsius.
When the magnet is heated even further, it will melt and turn into vapor, leading to a destroyed state.
What Magnets Can Withstand High Temperatures?
Whether you’re looking for a magnet to integrate with an instrument or machine that operates in high temperatures, knowing the magnets which can withstand high temperatures is essential.
AlNiCo permanent magnet is the first one of the magnets that can operate even when exposed to high temperatures. Its properties include aluminum, nickel, and cobalt, thus the name AlNiCo. This kind of magnet can withstand the heat of 600 degrees Celsius.
A neodymium magnet is another magnet that can keep its magnetic properties even when exposed to a higher temperature. It is known for being a powerful magnet that can withstand the heat of up to 200 degrees Celsius. Neodymium magnets have reversible properties in which the magnetic properties return after cooling. However, it can be irreversible when exposed to heat that reaches Curie’s point. As a result, parts of the magnet will be compromised and can possibly be demagnetized.
Ferrite Magnet is also one of the powerful magnets that are made of high-quality metals. Due to its extreme magnetic properties, it can also operate well with high temperatures of up to 180 degrees Celsius. Although, like any other magnet, it will begin to lose its properties when the temperature reaches more than its Currie point.
Can You Re-magnetize The Magnets After Being Heated?
There are times when you’ve exposed your magnets to extreme heat other means for its magnetic properties to wear off. This is entirely possible as long as you have not entirely reached the optimum temperature for the magnetic dipoles to be totally destroyed.
You can identify if your magnetic domains are still sticking together if your magnet still has a weak magnetic force. There is one way to strengthen and restore your magnet to its optimum strength – through the use of a neodymium pole.
Identify which part of your magnet is the north and south poles, and rub the neodymium pole on the opposite side one after the other. Once done, you can see that your magnet is good as new!
You can also store the weakened magnets alternatively to help them restore their magnetic pole alignments over time. Then, position them with their north and south pole touching each other to restore and preserve their magnetic poles.
Temperature and its Effect on Magnets
We have now established that extremely high temperatures destroy a magnet’s electromagnetic properties. However, does it apply to all temperature range?
The short answer is yes. Since hot temperatures elevate the magnet’s particles to a high active degree, the atoms scatter and take too much space. This results in the destruction of the attractive force resulting from the misalignment of the magnetic domains within.
The opposite applies to magnets exposed to frigid temperatures. Take note that the lower the temperature is, the lesser probability that the atomic particles of an object will move. This applies to any state of matter and is most apparent in liquids turning into solid states.
When subjected to low temperatures, the magnetic fields are enhanced, and the force is strengthened. Demagnetization also has a hard time occurring since the forces are tightly knit together.
Since magnets are made from different materials, the temperature to which their magnetic properties can be altered varies according to the metals incorporated. This also applies to magnetic strength, as some magnets are made with metals with absolutely high attractive force.
Some of these magnets and their preferred optimum temperature for stronger magnetic forces are:
Neodymium Magnets – known for their durability in extreme conditions, this magnet performs well in low temperatures. This rare-earth magnet can function between 125 to 150 degrees Celsius and has a Curie temperature ranging from 310 to 400 degrees Celsius.
Alnico Magnets – can perform greatly in extremely high temperatures. They can operate up to 525 degree Celsius and has a Curie point of 800 degrees.
Electromagnets – temporary magnets that function best with regular room temperature. Extreme heat causes degradation, and extreme cold can yield to excessive lowering of wire resistance.
Freezing a Magnet: What will happen?
Now that we have answered what happens when a magnet is heated, some may inevitably be curious as to the results of freezing a magnet will yield.
Atomic particles within the atom tend to stick closely together with the higher the temperature is. While the effect is not prominent contrary to the magnet’s exposure to extreme heat, the cold can also alter the magnet’s attractive properties.
However, increasing the temperature to a higher degree does not mean the magnet’s strength will increase infinitely. This is because once the temperature reaches -185 degrees, a change in the magnetic particles occurs.
This is called spin reorientation, which is the change of the magnetic domains’ alignments. The magnetic properties will decrease continuously at this point and will result in total demagnetization.
Magnets, like all other objects that exist, are susceptible to temperature changes. This is because their particles are also affected by changes in temperature.
When exposed to high temperatures, the magnetic particles behave randomly, resulting in the magnetic poles losing their alignment. Once the negative and positive poles domains no longer align, the magnetic properties wear off. Constant temperature increase can ultimately destroy a magnet once it surpasses its threshold, called the Curie point.
Low temperatures yield the opposite effect. This is because the cold promotes the atomic particles to stick together, further strengthening the magnetic force. However, there is also a limit to the increase of attractive strengths. Once the temperature decreases to a certain degree, the tightly-knit atomic particles gradually lose their forms and undergo demagnetization.
While temperature is a great factor for a magnet to undergo molecular changes, the material is also something to consider. Please note that the components of a magnet have a significant effect on its optimum functional temperatures and can also vary on their Curie points.
Heat is the strongest key in demagnetization, and it also has the most significant effects on a magnet’s longevity and lifespan. There are various ways to restore a magnet, given that its magnetic domains are not totally destroyed by extreme temperatures.