Alnico magnets are often selected for high-temperature applications because their magnetic output is exceptionally stable across temperature compared with many other permanent-magnet materials. That does not mean Alnico is automatically the best choice for every hot environment: its relatively low coercivity makes geometry and magnetic-circuit design especially important.
Why Alnico Performs Well at High Temperature
Alnico has a very low reversible temperature coefficient of magnetic induction, which helps it maintain stable magnetic output as temperature changes. This is one reason it remains useful in sensors, instruments, motors, generators and other applications where repeatability matters.
Radial’s stocked Alnico 5 products are currently specified with an 800°F stability temperature. Actual allowable operating temperature should still be validated for the specific grade, geometry, magnetic circuit and required performance margin.
The Tradeoff: Lower Coercivity
Alnico’s main limitation is not temperature—it is relatively low coercivity. A short magnet in an open magnetic circuit can be more vulnerable to partial demagnetization than a comparable NdFeB, SmCo or ferrite magnet.
Designs using Alnico often benefit from favorable length-to-diameter ratios, pole pieces or return paths that keep the magnet operating at a suitable permeance coefficient.
Alnico vs. High-Temperature NdFeB and SmCo
| Material | Best known for | Main limitation |
|---|---|---|
| Alnico | Excellent temperature stability and high residual induction | Lower coercivity; circuit design matters |
| High-temperature NdFeB | High magnetic strength in a compact size | Grade-dependent temperature limit and corrosion protection |
| SmCo | High-temperature capability plus high coercivity and good corrosion resistance | Higher material cost and brittleness |
For a broader material comparison, see our Types of Magnets guide.
When Alnico Is a Good Choice
- Temperature stability is a primary requirement.
- The magnetic circuit can support Alnico’s lower coercivity.
- Good corrosion resistance is desirable.
- Rod, bar, block or custom cast shapes are practical.
- Stable field output matters more than maximizing force per unit volume.
When Another Material May Be Better
Use high-temperature NdFeB when compact size and high magnetic force are the priority. Consider SmCo when you need high-temperature performance together with much higher coercivity and excellent environmental resistance. Ferrite can be attractive when cost and corrosion resistance dominate and the larger size is acceptable.
Stock Alnico 5 Magnets
- SKU 9756 — Alnico 5 rod, 1/8″ × 0.4687″
- SKU 8655 — Alnico 5 block, 2″ × 1″ × 3/8″
- SKU 8610 — Alnico 5 rod, 3/8″ × 3″
For the full material overview, read our Alnico Permanent Magnets Buying Guide, or browse Alnico stock.
Need Help Choosing a High-Temperature Magnet?
If you have operating temperature, geometry, air-gap and performance requirements, use the Magnet RFQ Builder. For production quantities, submit a Bulk Magnet RFQ.
