Hey there! Have you ever wondered exactly why some metals seem attracted to magnets? I used to be curious about what makes iron stick to a refrigerator magnet, while aluminum feels no pull.
The truth is that magnetism arises from some fascinating physics at the atomic scale inside certain metals. And this atomic-level magnetism is what makes bulk metals seem magnetic to us.
In this guide, we‘ll unpack what makes metals magnetic while avoiding scary physics jargon. I‘ll focus on explaining concepts simply as if chatting with a friend. Sound good?
Here‘s a quick roadmap of what we‘ll cover:
- Origin of magnetism in metals at the atomic level
- Different categories of magnetism
- The only 3 ferromagnetic metal elements
- Various ferromagnetic metal alloys
- Surprising magnetic non-metals
- Cutting-edge applications from MRI machines to quantum computing
Let‘s get started!
Magnetism Starts with Spinning Subatomic Particles
Magnetism might seem like a strange, almost supernatural force. But it actually arises from the predictable physics of tiny subatomic particles inside atoms.
You‘re probably familiar with electrons – negativity-charged particles spinning around an atom‘s nucleus. Turns out electron spin direction helps create magnetism, along with the orbits of protons in the nucleus.
When lots of electron spins align in the same direction, they collectively produce their own tiny magnetic field. The same is true for many spinning protons.
Within a magnetic metal, billions of atoms contribute these miniature magnetic fields. Together they create the larger-scale field that we sense when a fridge magnet sticks. Pretty cool how such invisible micro-forces manifest visibly!
This atomic alignment that produces macro-level magnetism tends to happen more in some elements than others. Let‘s explore why…
The 4 Flavors of Magnetism
Believe it or not there are 4 types of magnetism. From strongest attraction to actual repulsion:
- Ferromagnetism – Strong attraction to magnets
- Paramagnetism – Weak attraction
- Diamagnetism – Weak repulsion
- Antiferromagnetism – Cancellation leads to no magnetism
As you may guess, ferromagnets are the superstars here. Their atomic-scale magnetic fields energetically cooperate to create crazy strong magnetic forces on our human scale.
Let‘s now survey which metals actually demonstrate ferromagnetic tendencies intrinsically…
Just 3 Elemental Metals Are Ferromagnetic
Most pure metals are weakly magnetic – either para- or diamagnetic. But only 3 elements on the entire periodic table are ferromagnetic:
Iron 🏋️♂️
Nickel 🥈
Cobalt ⚛️
These metals have strong atomic-scale magnetic fields that reinforce each other, leading to the strong macro magnets we‘re familiar with.
For example, iron demonstrates the highest saturation magnetization among elements – 2.2 tesla. That‘s seriously magnetic!
Nickel and cobalt also have impressively high magnetic moments of 0.62 and 1.88 tesla respectively. No wonder early compasses used naturally magnetic lodestone containing iron-rich minerals!
Now the catch is that ferromagnetism fades away at higher temperatures. As heat jostles the neatly aligned atoms, their magnetic cooperation breaks down.
The maximum temperature where a metal retains ferromagnetism is called its Curie point. Above this the material becomes merely paramagnetic.
For instance nickel has a modest Curie point of just 627 K (354°C). But iron and cobalt persist as ferromagnets to 1,043 K and 1,388 K thanks to stronger atomic binding.
This thermal robustness makes cobalt useful in jet engine turbines and other scorching applications needing magnetism!
Magnetic Metal Alloys
Combining multiple metals into an alloy unlocks all sorts of novel mechanical, thermal, and…magnetic properties!
Many ferromagnetic alloys demonstrate improved strength, corrosion resistance, or high temperature stability compared to their pure constituents. Some noteworthy examples include:
| Alloy | Composition | Notes |
|---|---|---|
| Permalloy | Iron + Nickel | Tunable permeability |
| Steel | Iron + Carbon | The classic alloy we all know |
| Alnico | Aluminum + Nickel + Cobalt + Iron | Powerful multipolar magnets |
One downside is that more complex alloys have lower Curie points than pure iron generally. But we can tailor magnetic performance for specialized applications with the right recipe!
Magnets Without Metals??
Given everything we‘ve discussed, it may surprise you to learn some non-metals also demonstrate magnetic tendencies!
For instance liquid oxygen becomes paramagnetic at cryogenic temperatures – probably from dumbbell-shaped molecule formation. And even organic compounds like boron fullerenes display a weak magnetic response in laboratory conditions.
While not conventionally thought of as magnetic, these non-metals illustrate that under the right circumstances magnetism can emerge from unlikely places!
Cutting-Edge Applications
Now that you understand what makes metals magnetic on a microscopic level, let‘s survey some ways we apply those properties in the modern world:
MRI Scanners 🧠️ – Require incredibly strong superconducting magnets utilizing exotic niobium-tin or niobium-titanium alloys cooled close to absolute zero!
Quantum Computing 💻 – New experimental techniques involve detecting single unpaired electrons within ferromagnetic hafnium films to enable quantum logic.
Hyperloop Transport ⚡️ – Futuristic vacuum tube vehicles like the Hyperloop may levitate using an inductrack – a passive magnetic levitation system using Halbach arrays of permanent magnets.
And many more nascent technologies are unlocking new capabilities with exotic magnetic metals! The future looks bright…and magnetic 😊
So in summary, while magnetism itself seems occult and mysterious, it actually emerges from an elegant physics of spinning subatomic particles. A few special metals like iron and cobalt display strong intrinsic ferromagnetism that profoundly impacts our advanced devices and tools.
I hope this guide has helped demystify what makes metals magnetic! Let me know if you have any other questions.
