Alnico magnets are iron-based permanent magnets containing aluminum, nickel and cobalt, with grade-dependent additions such as copper or titanium. They are valued for excellent temperature stability, high residual magnetic induction and good corrosion resistance. Their main design limitation is relatively low coercivity compared with rare-earth and ferrite magnets, so geometry and the magnetic circuit matter.
For buyers and engineers, Alnico is especially useful when stable magnetic output at elevated temperature is more important than achieving the highest possible magnetic strength in the smallest package. If you are sourcing standard Alnico 5 parts now, browse stocked Alnico magnets; for material selection and design guidance, continue below.
What Is an Alnico Permanent Magnet?
Alnico was one of the first high-performance permanent-magnet material families. The name comes from aluminum (Al), nickel (Ni) and cobalt (Co); iron is the primary balance of the alloy, with other elements added depending on grade.
Unlike an electromagnet, an Alnico magnet retains useful magnetization without continuous electrical power. Alnico parts are commonly produced by casting or sintering, then finish-ground where tighter tolerances are required.
Alnico Magnet Properties at a Glance
| Property | Alnico behavior | Engineering significance |
|---|---|---|
| Residual induction (Br) | High | Can produce strong useful flux in a well-designed magnetic circuit |
| Coercivity | Relatively low | More sensitive to demagnetizing fields and unfavorable length-to-diameter ratios than NdFeB, SmCo or ferrite |
| Temperature stability | Excellent | One of Alnico’s strongest advantages for elevated-temperature applications |
| Corrosion resistance | Generally good | Often used without a protective plating in ordinary environments |
| Mechanical behavior | Hard and brittle | Conventional drilling or machining is generally not appropriate after manufacture |
| Electrical conductivity | Conductive | Unlike ferrite, Alnico is electrically conductive |
Why Alnico’s Low Coercivity Matters
A common misconception is that Alnico is highly resistant to demagnetization. In fact, compared with modern rare-earth and ferrite magnets, Alnico typically has lower coercivity. That means the magnet’s proportions and surrounding steel path must be considered carefully.
Longer magnetic lengths, favorable permeance coefficients and closed or semi-closed magnetic circuits can help Alnico operate reliably. Short, open-circuit shapes may be more vulnerable to partial demagnetization from external fields or handling conditions.
Alnico Grades
Alnico is available in multiple grades, including Alnico 2, 3, 4, 5, 6, 8 and 9. Different grades trade off residual induction, coercivity, energy product and preferred magnetization direction.
Alnico 5 is one of the most widely used grades and is the grade currently stocked by Radial Magnets. Anisotropic Alnico grades are oriented during heat treatment to achieve stronger magnetic properties in a preferred direction.
Alnico vs. Neodymium, SmCo and Ferrite
| Material | Relative magnetic strength | Temperature capability | Corrosion resistance | Coercivity |
|---|---|---|---|---|
| Alnico | Moderate | Very high | Good | Lower |
| NdFeB | Highest | Grade-dependent | Usually needs coating | High |
| SmCo | High | High | Excellent in many environments | High |
| Ferrite | Lower | Good | Excellent | High |
For a broader comparison, see our Types of Magnets guide.
Where Alnico Magnets Are Used
- Sensors and instruments: applications where repeatable magnetic output and temperature stability are important.
- Audio equipment: guitar pickups, loudspeakers and microphones where Alnico remains widely recognized.
- High-temperature equipment: systems where standard NdFeB grades may not provide sufficient thermal margin.
- Motors and generators: selected magnetic circuits where Alnico’s flux density and temperature behavior fit the design.
- Holding and measurement devices: specialized gauges, meters and magnetic fixtures.
Stock Alnico 5 Magnets at Radial Magnets
Radial currently carries three Alnico 5 stock parts:
- SKU 9756 — Alnico 5 rod, 1/8″ diameter × 0.4687″
- SKU 8655 — Alnico 5 block, 2″ × 1″ × 3/8″
- SKU 8610 — Alnico 5 rod, 3/8″ diameter × 3″
Browse the full Alnico Magnets category for current availability.
When Should You Choose Alnico?
Alnico is a strong candidate when:
- Temperature stability is a major design requirement.
- The magnetic circuit can support Alnico’s lower coercivity.
- Good corrosion resistance without extensive coating is desirable.
- A rod, bar, block or custom cast geometry is practical.
Alnico may be a poor fit when the design requires the highest possible force from a very small magnet, when the magnet will operate in a strongly demagnetizing open circuit, or when mechanical shock and brittle material are concerns.
Alnico for High-Temperature Applications
Alnico is often considered for elevated-temperature service because of its low reversible temperature coefficient and strong thermal stability. However, the actual allowable operating temperature still depends on grade, geometry, magnetic circuit and required performance margin. See our dedicated guide to Alnico magnets for high-temperature applications.
FAQ: Alnico Permanent Magnets
Are Alnico magnets permanent magnets?
Yes. Alnico is a permanent-magnet alloy family that retains useful magnetization without continuous electrical power.
Are Alnico magnets stronger than neodymium magnets?
No. NdFeB generally provides much higher magnetic energy density. Alnico’s advantages are temperature stability, high residual induction and good corrosion resistance.
Do Alnico magnets need plating?
Often they do not. Alnico is generally more corrosion resistant than NdFeB, although application-specific environmental testing may still be appropriate.
Can Alnico magnets be machined after magnetization?
Alnico is hard and brittle. Precision shaping is typically performed during manufacturing using casting, sintering and finish grinding rather than conventional drilling or cutting of a finished magnet.
Can Radial Magnets supply custom Alnico parts?
Yes. For custom geometry, grade, magnetization or production volumes, use the Magnet RFQ Builder or Bulk Magnet RFQ.
