In their natural states, metals such as brass, copper, gold and silver will not attract magnets. This is because they are weak metals to start with. Magnets only attach themselves to strong metals such as iron and cobalt and that is why not all types of metals can make magnets stick to them.
Electromagnetic Iron tends to machine more like copper than steel. Because Electromagnetic Iron is quite ductile, the chips tend to form continuous curls rather than breaking up. For this reason, it may be necessary to shape the tool to divert the chips in the manner desired. Good machining practices should be followed. Due to their properties such as superparamagnetism, high surface area, large surface-to-volume ratio, easy separation under external magnetic fields, iron magnetic nanoparticles have attracted much attention in the past few decades. Various modification methods have. What Metals Are Magnetic? Most metals with magnetic properties are ferrous: metals and alloys that contain iron. These ferrous metals include mild steel, carbon.
20.09.2019 by Andreas VellingMagnetic metals & non-magnetic metals both play an important role in engineering. Magnetism is the basis for many applications. At the same time, this property may also be unwanted in certain circumstances.
Therefore, it is important to know which metals are magnetic and which ones are not.
What is Magnetism?
In layman’s terms, magnetism is a force that can attract or repel magnetic objects. Magnetic fields that permeate different mediums mediate this force.
Magnetism is a property of certain materials by default. Some materials, though, can be magnetised or demagnetised depending on the requirements.
What Creates Magnetism in Metals?
Like an electric current, magnetism is caused by electrons at the elementary level. Electrons have spin, which creates a tiny magnetic dipole.
When these spins are balanced, the net force is zero. But in case of a large number of unpaired electrons, this infinitesimally small magnetic moment becomes large. As a result, it creates a noticeable magnetic field around the metal.
Electric current is also capable of creating magnetic fields and vice versa. When an electric current passes through a wire, it creates a circular magnetic field around the wire. Similarly, bringing a magnetic field near a good conductor of electricity, electric currents start flowing in the conductor.
This amazing relationship between electricity and magnetism has resulted in many ingenious devices and applications.
Types of Magnets
![Iron Iron](/uploads/1/3/4/7/134730521/959723237.jpg)
There are various classifications for magnets. One way to differentiate magnetic metals from each other is by how long their properties are active. Using this as our basis, we can classify magnets as:
- Permanent
- Temporary
- Electromagnets
Let’s take a deeper look into each of them.
Permanent Magnets
Permanent magnets produce a magnetic field due to their internal structure. They do not lose their magnetism easily. Permanent magnets are made of ferromagnetic materials that do not stop producing their magnetic field regardless of external influence. Thus, they are stable against demagnetising forces.
To understand permanent magnets, we must look at the internal structure of magnetic materials. A material displays magnetic properties when its domains are aligned in the same direction. Domains are the minuscule magnetic fields that are present in a material’s crystalline structure.
In ferromagnetic materials, the domains are perfectly aligned. There are various ways to align them but the most reliable method is to heat the magnet to a certain temperature. This temperature is different for materials and results in the permanent alignment of domains in one direction.
It is due to similar conditions existing in the earth’s core that it behaves like a permanent magnet.
Temporary Magnets
Temporary magnets, as the name suggests, only retain their magnetic properties under certain conditions. When these conditions are no longer present, they lose their magnetic fields.
Soft materials with low magnetic properties, such as annealed iron and steel, are examples of temporary magnets. They become magnetic in the presence of a strong magnetic field. They also portray low coercivity.
You must have seen how paper clips get attached to each other when a permanent magnet is nearby. Every paper clip becomes a temporary magnet attracting other paper clips in the presence of a magnetic field. Once the permanent magnet is taken away, the paper clips lose their magnetic properties.
Electromagnets
Electromagnets are magnets that produce magnetic fields when an electric current passes through them. They have various use-cases. For example, motors, generators, relays, headphones, etc. all use electromagnets.
In electromagnets a coil of wire winds around a ferromagnetic core. Connecting the wire to a source of electricity produces a strong magnetic field. The ferromagnetic material further amplifies it. Electromagnets can be extremely strong depending on the electric current.
They also provide the ability to turn the magnetic force on and off with the press of a button. This is an extremely special property that helps us to use the magnetic force in our applications.
Let’s take the example of a crane used to pick up scrap metal in a junkyard. With the help of an electromagnet, we can pick up the scrap metal by passing an electric current through it. When we need to drop the pieces, all we have to do is turn off the electricity to the magnet.
Another interesting example of an electromagnet application is the Maglev train. In this application, a train lifts off the tracks and levitates. It is only possible when an electric current runs through electromagnets on the train body.
This considerably reduces the resistance faced by the train when in motion. Hence, these trains have very high velocities.
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Which Metals Are Magnetic?
There are various ways in which a metal may interact with a magnet. This depends on the internal structure of the materials. Metals can be classified as:
- Ferromagnetic
- Paramagnetic
- Diamagnetic
While magnets strongly attract ferromagnetic metals, they only weakly attract paramagnetic metals. Diamagnetic materials, on the other hand, show a weak repulsion when placed near a magnet. Only ferromagnetic metals are considered truly magnetic.
List of Magnetic Metals
Let’s take a look at some of the most well known magnetic metals. Some of them are magnetic at all times. Other, like stainless steel, have magnetic properties only with a certain chemical composition.
Iron
Iron is an extremely well-known ferromagnetic metal. It is, in fact, the strongest ferromagnetic metal. It forms an integral part of the earth’s core and imparts its magnetic properties to our planet. That is why the Earth acts as a permanent magnet on its own.
There are many aspects that contribute to iron’s magnetism. In addition to its net electron spin at the atomic level, its crystalline structure also plays an important role. Without it, iron would not be a magnetic metal.
Different crystalline structures result in different iron properties.
Iron is ferromagnetic in its body-centred cubic (bcc) alpha-FE structure. At the same time, it does not show magnetism in face-centred cubic (fcc) gamma-Fe structure. Beta-Fe structure, for example, displays paramagnetic tendencies.
Nickel
Nickel is another popular magnetic metal with ferromagnetic properties. Like iron, its compounds are present in the earth’s core. Historically, nickel has been used to make coins.
Today, nickel finds use in batteries, coatings, kitchen tools, phones, buildings, transport and jewellery. A large portion of nickel is used to manufacture ferronickel for stainless steel.
Because of its magnetic properties, nickel is also part of Alnico magnets (made of aluminium, nickel, and cobalt). These magnets are stronger than rare-earth metal magnets but weaker than iron-based magnets.
Cobalt
Cobalt is an important ferromagnetic metal. For over 100 years, cobalt’s excellent magnetic properties have helped develop a variety of applications.
Cobalt can be used to produce soft as well as hard magnets. Soft magnets that use cobalt have advantages over other soft magnets. Namely, they have a high saturation point, Curie temperatures in the range of 950…990° Celsius. Thus, they can be used for high-temperature applications (up to under 500° Celsius).
Cobalt with its alloys is used in hard disks, wind turbines, MRI machines, motors, actuators, and sensors.
Steel
Steel also displays ferromagnetic properties as it is derived from iron. Most steels will be attracted to a magnet. If needed, steel can also be used to make permanent magnets.
Let’s take the example of steel EN C15D. This grade of steel contains 98.81 to 99.26% iron. Thus, a very high percentage of this steel grade is iron. Hence, the ferromagnetic properties of iron transfer to steel.
Iron Magnetic Saturation
Stainless Steel
Some stainless steels are magnetic and some are not. An alloy steel becomes a stainless steel if it has at least 10.5% of chromium in it. Due to the varying chemical compositions, there are different types of stainless steel.
Ferritic and martensitic stainless steels are magnetic due to their iron composition and molecular structure.
Austenitic steels, on the other hand, do not display ferromagnetic properties because of a different molecular structure. This makes the suitable for use in MRI machinery.
The structural difference derives from the amount of nickel. It strengthens the oxide layer for better protection against corrosion but also changes the structure of stainless steel.
Rare Earth Metals
Along with the above-mentioned metals, compounds of some rare earth elements also have excellent ferromagnetic properties. Gadolinium, samarium, neodymium are all examples of magnetic rare earth metals.
Various magnets with different properties can be manufactured using the above metals in combination with iron, nickel and cobalt. These magnets come with specific properties necessary for certain applications.
For example, samarium-cobalt magnets are present in turbomachinery, high-end electric motors, etc.
Which Metals Are Not Magnetic?
Only a few metals in the periodic table are magnetic. Most other common metals are non-magnetic metals. Let’s take a look at some of them.
List of Non-Magnetic Metals
Aluminium
Aluminium’s crystal structure, similarly to lithium and magnesium, makes it non-magnetic. All three materials are popular examples of paramagnetic metals.
Although several types of aluminium corrosion can happen, it is known for its resistance to corrosive environments. This, along with its light weight, makes it a useful metal in many industries.
Gold
Gold is a diamagnetic metal like most other metals. In its pure form, gold is non-magnetic and shows only a weak repulsion towards magnets like all diamagnetic metals.
Silver
Silver is another non-magnetic metal. This property makes identifying fake silver possible. If the “silver” coins or jewellery attracts to magnets, it is something else.
Copper
Copper itself is not magnetic but interacts with magnets to some extent. This property helps generate electricity in power plants.
Conclusion
With a large enough magnetic field, all types of metals will interact with a magnet. This is because eddy currents are set up in metals when they are subjected to a moving magnetic field.
Using this principle, metal detectors are able to detect non-magnetic metals like gold, silver. But for most practical purposes, this interaction is not enough and limits the possible use-cases.
Magnetic Cereal
Magnets Reveal Hidden Cereal Ingredient!
Many cereals are fortified with added iron, one of many necessary vitamins and minerals. These items are added to the mix when the cereal is are made, so it is a bit like taking your vitamin with the cereal.
Since iron is attracted to magnets, finding it can be an instructive science experiment. We like it because we’re experimenting with new ideas using everyday stuff that most people are already familiar with. If you're using strong magnets to try this experiment with kids, be sure to include adult supervision. Strong magnets are not toys!
What is Food Fortification?
Food that is fortified has vitamins and minerals added to it for their health benefits. Fortified cereals are a well known example.
While there are arguments for and against it, foritification has definitely addressed a number of large-scale, across-the-population epidemics. A well-known example is iodized salt, which was introduced in 1924. Adding iodine to salt has reduced Idodine Deficiency Disorder (IDD), occurence of mental retardation, hypothyroidism and goiter. Another example is the addition of Vitamin D to milk, margarine and cereals. This has reduced bone deformations, rickets, and other health problems associated with Vitamin D deficiencies.
These things have been working for so long, we're no longer even familiar with some of the once common diseases they have prevented.
For the record, the iron in your cereal isn’t really hidden – Iron is listed right on the box as an added ingredient.
How much iron is in there?
In one serving of cereal, there is a pretty tiny amount of iron added. How much is there? Let’s see if we can make an educated guess.
The side of that Life cereal box says that one serving contains 50% of the daily requirement. How much is that? Well, what’s recommended for you depends on your age and gender. According to this source, it can vary from about 8 to 18 mg (milligrams) per day. We’re not sure what number the cereal box is basing its numbers on, but it’s probably somewhere in this range.
How much iron is 8-18 mg? That’s hard to visualize. We don’t deal with milligrams enough in our daily lives to be able to picture that. If it were a solid cube of raw iron, how big would it be? If our math is right, we’re figuring it would be a cube of iron that is about 1mm square. That’s tiny!
Of course, in the cereal this iron is ground into a find dust and spread throughout. Let’s see if we can find it hidden in there.
Magnetic Property Of Iron
Grind the cereal & find evidence of iron
Crushing the cereal
We started with dry cereal and crushed it into a fine powder with a mallet. The smaller the pieces you can grind it into, the better these experiments will work. In the pictures and videos that follow, we did not go to extraordinary lengths to make the grinding too fine. (We used the patience level of a few kids to judge when it was done.)
As a first try, we simply rubbed the end of a magnet around in the crushed cereal. Sure enough, some of the cereal stuck to the edges of the magnet. Since that's where the magnetic field is strongest, it makes sense that it sticks there.
We found that a few pieces of cereal dust stuck to the edges of the XLTK-YEL magnetic thumbtack and the B666 block magnets we tested with. There’s nothing special about using those two blocks – we just had them handy at home from a TIN1 sample pack of magnets.
We also suggest simple cylinder magnets like the D6C or strong D8C magnets for this sort of check.
Move the cereal around
We also were successful in seeing evidence of the iron by moving a magnet around underneath the paper plate. Slowly moving it around made a few tiny pieces of cereal move around to follow the magnet.
Can we make it more obvious?
Seeing that bit of cereal move around is somewhat subtle. Unless you’re really looking up close, you might not easily see it. Can we make the motion of the cereal more obvious?
We sprinkled a little of the cereal across the top of a shallow bowl full of water. Some of the cereal floated on top. By moving a magnet near the cereal, but not touching the cereal or water, we can make clumps of the cereal move toward the magnet. It is fairly obvious how the clumps of cereal sail across the top of the water!
We used D68PC-RB and B666 magnets to demonstrate, plus a dangerously strong DCY0 cylinder. If you use really large magnets like this, be careful handling them! They are not for kids, and can be dangerous if allowed to slam into other objects or magnets.
Get the iron out of the cereal so we can see it firsthand.
Cereal and water in a Ziplock bag
Up to this point, everything we’ve seen is good evidence that there is iron in the cereal, but we have not seen the actual iron. We have seen it attracted to and moved towards a magnet, but the iron remained embedded within the tiny particles of cereal.
Now let’s see if we can separate the iron from the cereal using magnets. To do this, we put the serving of cereal in a ziplock back along with some water. Let this sit for a while, perhaps 20 minutes or so. This allows the cereal to soften into a soggy mush.
After a while, take a strong magnet and move it slowly around the cereal mush from the outside of the bag. We set the magnet on the table and set the bag on top of it, then slushed the mixture around slowly. After a while of this, we found a little bit of black iron dust stuck right to the magnet! In the video below, you can clearly see this bit of iron moving around to stick to the magnet.
This is a great science experiment for all ages. Adult supervision recommend with strong magnets!
![Iron Magnetic Iron Magnetic](/uploads/1/3/4/7/134730521/596310548.jpg)