Heat Resistance Comparison: How Different Magnets Handle Temperature

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Temperature is a big deal when it comes to magnets—it directly affects their magnetic strength. We covered this in detail in our previous article What Factors Cause Demagnetization of Permanent Magnets?, so we won't rehash it here.

But here's the thing: different magnets handle heat very differently. And then, of course, when you're selecting a magnet, heat resistance is probably the second most important factor after the actual magnetic performance.

The Key Measures of Heat Resistance

First, let's talk about what we mean by heat resistance in a general way, so we can compare the performance of different magnets with respect to heat resistance. There are really two important figures that tell you how well a given magnet works at high temperatures: Maximum Operating Temperature and Curie Temperature.

First, we have the maximum operating temperature. This is the maximum temperature at which a magnet can operate. When you exceed this limit, the performance of the magnet starts to degrade.

Then we have the Curie temperature. This is the point at which a magnet loses its magnetism altogether. When you exceed this point, the magnet loses its magnetism altogether and cannot be restored by reducing the temperature.

In real-world use, magnets usually start losing magnetism irreversibly well before hitting their Curie temperature. So the maximum operating temperature is the more practical number to pay attention to.

Heat Resistance by Magnet Type

1. Neodymium (NdFeB) Magnets

Let's start with neodymium—the strongest magnets on the market. Even within the same family, different grades handle heat differently.

Grade	Max Operating Temp	Curie Temp	What It's About
N (Standard)	About 80°C	About 310°C	Strongest magnetism, but least heat-resistant
M	About 100°C	About 340°C	A bit of heavy rare earth added
H	About 120°C	About 360°C	Common in regular motors
SH	About 150°C	About 380°C	Often used in hybrid vehicles
UH	About 180°C	About 400°C	Common in electric vehicles
EH	About 200°C	About 410°C	High-performance EVs
AH	About 220°C	About 430°C	Extreme high-temp applications

You can boost neodymium's heat resistance by adding heavy rare earth elements like dysprosium or terbium. But that comes at a cost—it lowers the magnetic strength a bit and definitely raises the price.

2. Samarium Cobalt (SmCo) Magnets

Samarium cobalt magnets aren't quite as strong as neodymium, but they're absolute champs when it comes to high temperatures.

Type	Max Operating Temp	Curie Temp	What It's About
SmCo5 (1:5 type)	About 250–300°C	About 720°C	Excellent heat resistance
Sm2Co17 (2:17 type)	About 300–350°C	About 800–850°C	Stronger magnetism, even better heat resistance

SmCo magnets blow neodymium out of the water when it comes to heat resistance. They also have a low temperature coefficient, meaning their strength drops slowly as temps rise. The trade-off? They're a bit weaker magnetically and more expensive.

3. Alnico Magnets

Alnico magnets are another common type you'll run into.

Type	Max Operating Temp	Curie Temp	What It's About
Alnico	About 450–550°C	About 800–860°C	Excellent heat resistance

Alnico handles heat really well, but it's not super strong magnetically, and it has very low coercivity—meaning it's easy to accidentally demagnetize. So in practice, it's not always as stable as samarium cobalt.

4. Ferrite (Ceramic) Magnets

Type	Max Operating Temp	Curie Temp	What It's About
Ferrite	About 250°C	About 450°C	Decent heat resistance

Ferrite magnets handle heat better than standard neodymium, but they're not as strong. One nice thing about them is that their demagnetization curve is linear at high temps, so they're pretty resistant to being accidentally demagnetized.

5. Neodymium-Iron-Nitrogen (NdFeN) Magnets

Type	Max Operating Temp	Curie Temp	What It's About
NdFeN	About 150°C	About 470°C	Newer material, not yet widely available

This is a newer type of permanent magnet. Its heat resistance falls somewhere between neodymium and samarium cobalt, but it's still not produced on a large scale.

Heat Resistance at a Glance

Here's how all the major magnet types stack up when it comes to handling heat.

Magnet Type	Max Operating Temp	Curie Temp	Rank	Notes
Alnico	450–550°C	800–860°C	#1	Best heat resistance, but low coercivity
Sm2Co17 (Samarium Cobalt)	300–350°C	800–850°C	#2	Stable performance at high temps
SmCo5 (Samarium Cobalt)	250–300°C	720°C	#3	Excellent heat resistance
Ferrite	250°C	450°C	#4	Decent heat resistance, weaker magnetism
NdFeB (AH grade)	220°C	430°C	#5	High-temp neodymium
NdFeB (EH grade)	200°C	410°C	#6	Common in EVs
NdFeB (UH grade)	180°C	400°C	#7	Common in hybrids
NdFeB (SH grade)	150°C	380°C	#8	Used in standard motors
NdFeB (N grade)	80°C	310°C	#9	Strongest magnetism, worst heat resistance

How to Choose Based on Temperature

Different applications need different levels of heat resistance. Here's a quick guide:

Application	Typical Operating Temp	Recommended Magnet
Fridge magnets, novelty items	Room temperature	Ferrite, NdFeB N-grade
Consumer electronics	40–60°C	NdFeB N/M
Industrial motors	80–120°C	NdFeB H/SH
EV drive motors	120–180°C	NdFeB UH/EH
Hybrid vehicle motors	150–200°C	NdFeB EH/AH
Aerospace sensors	200–300°C	Samarium cobalt
Oil drilling equipment	200–350°C	Samarium cobalt, alnico
High-temp instruments	400°C and up	Alnico

A Common Misconception

A lot of people think that a higher Curie temperature automatically means a magnet is better for high-temp applications. But that's not quite how it works.

In practice, magnets start to lose their magnetism irreversibly well before hitting the Curie temperature. Here's what I mean:

Alnico has a super-high Curie temperature (around 850°C), but its coercivity is so low that a big current spike can demagnetize it in use.
Neodymium's Curie temp is only 310–430°C, but by adding heavy rare earths, it can actually operate at up to 220°C.

So when you're picking a magnet for a hot environment, the maximum operating temperature is a much better guide than Curie temperature alone.

In the End

If you need the strongest magnetic force possible, go with neodymium. If you need to survive high temperatures, samarium cobalt or alnico are your best bets. You rarely get both in one magnet.

If you have questions about choosing a magnet or figuring out what works for your application, feel free to reach out to Stanford Magnets. We can also help with pricing for the magnet you have in mind. GET A QUOTE

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About the author

Cathy Marchio

Cathy Marchio is an expert at Stanford Magnets, where she shares her deep knowledge of magnets like Neodymium and Samarium Cobalt. With a background in materials science, Cathy writes articles and guides that make complex topics easier to understand. She helps people learn about magnets and their uses in different industries, making her a key part of the company's success.

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