AlNiCo (aluminum-nickel-cobalt) magnets in cast and sintered forms. The most temperature-stable permanent magnet material available, with reversible temperature coefficient as low as −0.02%/°C. Specified for sensors, instrumentation, aerospace and high-temperature applications.
Operates continuously at 525–550°C — well above any rare-earth or ferrite material.
Reversible temperature coefficient as low as −0.02%/°C — flux holds across wide temperature ranges.
Cast AlNiCo for complex shapes, sintered AlNiCo for tight tolerances and small parts.
Cast and sintered forms for instrumentation, sensors and high-temperature duty.
Complex geometry produced by the cast route
Small parts with tighter dimensional control
Ring geometry for instrumentation
Segment geometry for legacy magnetic circuits
The tables below preserve the legacy empiremagnets.com product information and reference values. Use them for first-pass selection; final acceptance values remain project-specific.
| Application | Typical Spec | Why this material |
|---|---|---|
| Precision instruments | Alnico 2 / 5 | Very low flux drift over temperature |
| Watt-hour meters | Alnico 5 | Long-term stable reference field |
| Reed switch actuation | Alnico 3 / 5 | Stable actuation across temperature |
| Radar / TWT / instruments | Alnico 8 / 9 | High-temperature stability |
| Educational / scientific | Alnico 2 | Classic rods / horseshoe forms |
| Route | Strength | Tolerance / shape logic | Typical use |
|---|---|---|---|
| Cast | Higher energy and complex castable forms | Larger geometry; grinding on functional surfaces | Horseshoes, meters, sensors, instruments |
| Sintered | Fine grain and repeatability for small parts | Smaller precision components | Miniature sensors, magnetic circuits, instruments |
| Grade / Route | Br | Hc | Hci | (BH)max | Max Operating Temp* | |
|---|---|---|---|---|---|---|
| Alnico 2 (Sintered) | 7.0 kG / 0.70 T | 500 Oe / 40 kA/m | ≥540 Oe / 43 kA/m | 1.5 MGOe / 12 kJ/m³ | 450°C | Datasheet |
| Alnico 5 (Sintered) | 11.0 / 1.10 | 600 / 48 | ≥600 / 48 | 4.25 / 34 | 450°C | Datasheet |
| Alnico 8 (Sintered) | 8.8 / 0.88 | 1530 / 121 | ≥1600 / 127 | 5.25 / 42 | 450°C | Datasheet |
| Alnico 5 (Cast) | 12.2 / 1.22 | 600 / 48 | 630 / 50 | 5.0 / 40 | 500°C | Datasheet |
| Alnico 5B (Cast) | 12.2 / 1.22 | 650 / 52 | 660 / 53 | 5.5 / 44 | 500°C | Datasheet |
| Alnico 5DG (Cast) | 12.5 / 1.25 | 690 / 55 | 700 / 56 | 6.5 / 52 | 500°C | Datasheet |
| Alnico 5-7 (Cast) | 13.0 / 1.30 | 700 / 56 | 740 / 59 | 7.5 / 60 | 525°C | Datasheet |
| Alnico 8-HC (Cast) | 7.0 / 0.70 | 1750 / 139 | 1750 / 139 | 4.5 / 36 | 525°C | Datasheet |
| Alnico 8 (Cast) | 8.2 / 0.82 | 1500 / 119 | 1600 / 127 | 5.0 / 40 | 525°C | Datasheet |
| Alnico 8B (Cast) | 8.8 / 0.88 | 1500 / 119 | 1650 / 131 | 5.5 / 44 | 525°C | Datasheet |
| Alnico 8C (Cast) | 9.0 / 0.90 | 1380 / 110 | 1440 / 115 | 7.5 / 60 | 525°C | Datasheet |
| Alnico 9 (Cast) | 10.5 / 1.05 | 1410 / 112 | 1440 / 139 | 9.0 / 72 | 525°C | Datasheet |
| Property | Sintered | Cast |
|---|---|---|
| Vickers hardness | ~440 | 440–620 |
| Density | 6.8–7.0 g/cm³ | 6.9–7.3 g/cm³ |
| Curie temperature | 810–860°C | 740–860°C |
| Specific resistance | 50–70 μΩ·cm | 45–75 μΩ·cm |
| Thermal expansion | 11.0–12.4 ×10⁻⁶/°C | 11.0–13.0 ×10⁻⁶/°C |
| Reversible temperature coefficient Br | ≈ −0.02 to −0.03%/°C | ≈ −0.02 to −0.03%/°C |
| Route | Typical Tolerance | Notes |
|---|---|---|
| As-cast | ±0.3–0.5 mm | Economical near-net shape |
| Ground | ±0.05 mm | Pole and mounting faces |
| Sintered | ±0.05 mm | Small precision parts |
| Machining | Grinding-focused | Hard/brittle alloy; functional surfaces are normally ground |
Reference values are reproduced from the legacy product pages. Confirm grade, test method, tolerance, coating, temperature class and inspection criteria against the released drawing and purchase specification.
A visual record of magnetic material and assembly manufacturing, inspection and packing.
Manufacturing 
Manufacturing 
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Manufacturing 
Inspection 
Packing AlNiCo earns consideration when temperature stability, low reversible temperature coefficient and long service life outweigh its relatively low coercivity and larger magnetic-circuit requirement.
A drawing alone may not define the magnetic requirement. These inputs help us recommend the right grade, geometry, coating and inspection plan instead of quoting a generic part.
Give the magnet temperature range, gradients, cycling rate and the allowable change in flux or sensitivity.
Provide opposing field, nearby steel, armature position and the worst-case open-circuit or fault condition.
State whether the part is cast or sintered, along with geometry, machining allowance, surface finish and appearance limits.
For sensors and instruments, define the output window, magnet-to-sensor distance, matching requirement and calibration method.
Inspection scope should follow the failure mode. We can align the report format, sample quantity and release criteria during drawing review.
Verify the magnetic output over the agreed temperature profile rather than accepting room-temperature data alone.
Test the worst-case opposing field or assembly condition and record the retained performance after exposure.
Inspect cast or sintered features against the drawing, including machining datum, porosity or visual limits where applicable.
For matched sets, define the measurement fixture, temperature point, sorting band and traceability record.
AlNiCo can be attractive when very stable temperature behavior, specific cast geometries or a legacy magnetic circuit are important. SmCo may be preferred when higher coercivity or a more compact design is needed.
It can, but the complete magnetic circuit must be evaluated because AlNiCo has relatively low coercivity. Nearby steel and opposing fields can change the working point.
The manufacturing route affects achievable geometry, dimensional control, surface finish and cost. The suitable route should be selected against the drawing and volume.
Our engineering team can review material, operating conditions, magnetic requirements, manufacturing route and validation needs before quotation.