Which Metals Have Magnetic Properties?

Magnets are something we are all aware of at a simple level, but exactly what metals are affected by them, and how they work? In this article, we take a look at which metals can be magnetized and what the different types of magnetism are.

What is a Magnet?

A magnet is defined as a metal that produces a magnetic field, and that can pull magnetic metals towards it. Only metals can become magnetic and be attracted to a magnet.

However, not all metals are magnetic and can be magnetized; there are specific qualities of metals that enable them to be magnetized. We’ll discuss this in greater detail later on.

What are the types of Magnets?

Magnets can be split into 3 categories:

• Permanent Magnets: These exhibit magnetic properties without needing an external source of magnetism or electrical power.
• Temporary Magnets: When metal becomes magnetic, but not permanently, such as when near another magnet, or an external magnetic field is applied
• Electromagnets: Another form of temporary magnets, these require an electric current passing through a coiled conductor to be magnetic.

What Metals Are Magnetic?

There are only 3 commonly used magnetic metals, along with some rare-earth ones, they are:

• Iron
• Cobalt
• Nickel
• Rare earth metals – Neodymium, Erbium, Dysprosium, Gadolinium and a few others

The property that allows these metals to be magnetic – ferromagnetism – is discussed further below.

Types of Magnetic Metals

We know magnets interact with certain metals, but not all metals act in the same way; for example, some repel when experiencing a magnetic field. These are the three main types of magnetic metal:

Ferromagnetic

Ferromagnetism is the action of a ferromagnetic material – those listed above – gaining magnetism when in the presence of a magnetic field and retaining that magnetism after the field is removed.

This is the type of magnetism most of us are familiar with and is what gives us permanent magnets. Common ferromagnetic materials are iron, steel, cobalt and nickel.

Paramagnetic

Paramagnetic materials are very slightly magnetic. When experiencing a magnetic field, they exhibit a very minor pulling force, which completely disappears when the magnetic field is removed.

Paramagnetic materials include but are not limited to: Aluminum, Magnesium and Titanium.

Diamagnetic

Diamagnetic materials have no attraction to a magnetic field; atomically, they may exhibit a force at 180° to the magnetic field – in other words, they repel.

Some diamagnetic materials include copper, wood, water and silver.

Properties of Magnetic Fields

Magnetic fields vary, depending on the type and strength of the source. There are, however, a few key constants with magnetic fields that can be observed regardless of strength or material:

• Magnetic fields have both strength and direction – magnetic fields exist in lines that emanate from one pole to another, they exist in 3 dimensions around the magnet
• Magnetic field lines never overlap – the field lines from a magnet always make complete circuits back to the magnet, and do not intersect or overlap
• The magnetic field is “stronger” closest to the magnet – However, all the field lines have the same strength, but the lines spread out the further out from the poles they are

Applications of Magnetic Metals

Magnetism is an incredibly useful property when making a component interact with other components in an assembly. Magnetic materials are used across industries in various ways.

Magnets For Retention

One of the more obvious uses of magnetic metals and permanent magnets is for holding a component or part in a certain position. This can range from a magnetic catch on a door or hatch to a magnetic sign or visual aid on a steel surface.

Magnetic Metals in Electronic Devices

Speakers are, in essence, a finely tuned electromagnet. An electrical current influences a magnetic field, introducing a vibration into a cone of metal or other material, which in turn causes sound vibrations to pass through the air.

Many speakers also use a permanent magnet made of ferrite or neodymium in their construction, and a coil from copper wire known as the voice coil.

Magnets in Switching

Solenoid valves are used throughout the engineering world to control fluid flow. They work using a coil of copper wire and a magnetic core made from steel. When energized, the coil induces a magnetic field and causes the core of the solenoid to move, acting as a connected valve.

Solenoid valves enable electrical control systems to control physical systems like gas and water flow.

Similarly, relays use a small electrical current to switch a larger current on and off, via an electromagnet switch. These are found in many electrical systems with high-current motors or other components.

Electric Motors

One of the most important components in enabling the modern world, electric motors, transform electrical energy into torque by creating a rotational electromagnet. Electric motors rely on the magnetic component of the steel stator to work.

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Whether you need ferromagnetic metals like steel or paramagnetic materials like aluminum, Metals Supermarkets has you covered, with a cut-to-size service available across stores nationwide.