Executive Summary
Curie temperature is an important parameter when engineers compare AlNiCo Magnet grades, but it should not be treated as the same value as maximum operating temperature. Nibboh’s technical table lists Curie temperature values from 810°C to 860°C for grades where TC data is provided, while the product page separately states that AlNiCo magnets have a maximum operating temperature exceeding 400°C. The listed grades also differ in remanence, coercive force, and maximum energy product, so Curie temperature should be read as one part of the complete magnetic specification rather than as a stand-alone selection value.
Curie Temperature vs Maximum Operating Temperature
One of the most important distinctions when reviewing AlNiCo specifications is the difference between Curie temperature and maximum operating temperature. On the Nibboh product page, these parameters are presented separately rather than as interchangeable values.
The grade table provides Curie temperature values between 810°C and 860°C for grades where TC data is specified. Separately, the product description states that AlNiCo magnets have a maximum operating temperature exceeding 400°C. For engineering and procurement teams, this means the Curie temperature shown in a grade table should not be interpreted as the recommended operating temperature of the magnet.
When reviewing a magnet for a generator, motor, instrument, sensor, or other industrial application, buyers should therefore distinguish between the material’s listed Curie temperature and its stated operating-temperature capability.
How Curie Temperature Varies Across AlNiCo Grades
AlNiCo is not represented by a single magnetic grade. Nibboh’s technical table lists multiple grades with different magnetic and temperature characteristics.
For example, the table specifies the following Curie temperatures for selected grades:
| Grade | Equivalent MMPA Class | Curie Temperature |
|---|---|---|
| LN10 | ALNICO3 | 810°C |
| LNG13 | ALNICO2 | 810°C |
| LNGT18 | ALNICO8 | 860°C |
| LNG37 | ALNICO5 | 850°C |
| LNG52 | ALNICO5DG | 850°C |
| LNG60 | ALNICO5-7 | 850°C |
| LNGT28 | ALNICO6 | 850°C |
| LNGT36J | ALNICO8HC | 860°C |
| LNGT38 | ALNICO8 | 860°C |
| LNGT60 | ALNICO9 | 860°C |
This variation is important because buyers should use the value associated with the specific grade under consideration rather than applying one Curie temperature to the entire AlNiCo product range. Some additional grades are listed on the product page without a Curie temperature value in the available table, so their temperature data should be confirmed rather than inferred from another grade.
Read Curie Temperature Together with Br, Hcb and (BH)max
Curie temperature is only one of the parameters that changes across the listed AlNiCo grades. The technical table also shows differences in remanence (Br), coercive force (Hcb), and maximum energy product ((BH)max).
Across the full grade table, the listed values range from:
- Remanence Br: 580–1350 mT
- Coercive force Hcb: 40–140 kA/m
- Maximum energy product (BH)max: 10–72 kJ/m³
These ranges show why selecting an AlNiCo grade only because it has a higher Curie temperature would be incomplete. Different grades combine temperature characteristics with different magnetic properties.
For example, LNGT36J is listed with a Curie temperature of 860°C, remanence of 700 mT, coercive force of 140 kA/m, and a maximum energy product of 36 kJ/m³. LNG52, by comparison, is listed with a Curie temperature of 850°C, remanence of 1300 mT, coercive force of 56 kA/m, and a maximum energy product of 52 kJ/m³. These figures illustrate that grades with similar high Curie temperatures can still have substantially different magnetic characteristics.
Why Temperature Coefficient Also Matters
The product page describes AlNiCo as a hard magnetic material with high remanence, a low temperature coefficient, and excellent magnetic stability. Its technical table also provides reversible temperature coefficient values for a number of grades.
This information should be considered alongside Curie temperature when reviewing grade data. Curie temperature identifies one temperature-related characteristic of the material, while the temperature coefficient provides additional information about how magnetic properties relate to temperature change for the listed grade.
Because these values vary between grades, engineers should compare the complete grade-specific data rather than selecting a magnet from Curie temperature alone.
What This Means for Generator and Motor Specification
Nibboh lists AlNiCo for applications including wind turbine generators, permanent magnet motors, instruments, sensors, and related industrial equipment. In these applications, the relevant grade should be evaluated against the magnetic and temperature requirements of the specific design.
A practical specification review can therefore begin with four questions:
- What Curie temperature is listed for the candidate grade?
- What Br, Hcb, and (BH)max values does that grade provide?
- What temperature coefficient data is available for the grade?
- Does the required operating condition fit the temperature capability stated for the AlNiCo product?
This approach keeps Curie temperature in context. Rather than treating the highest TC value as automatically preferable, engineers can compare temperature data with the magnetic characteristics required by the application.
Using the AlNiCo Grade Table for Procurement
For OEM and industrial buyers, a grade table is most useful when it is treated as a specification reference rather than a simple ranking from lower to higher performance. Nibboh lists AlNiCo grades with different combinations of Br, Hcb, (BH)max, density, temperature coefficients, and Curie temperature.
The AlNiCo Magnet product page also states that both cast and sintered AlNiCo magnets are available and that various shapes and sizes can be produced according to customer requirements. Once the required magnetic and temperature characteristics have been identified, buyers can use those requirements when discussing the appropriate grade and physical configuration for the intended application.
Where a value is not provided for a particular grade in the published technical table, it should be confirmed with the supplier rather than estimated from another AlNiCo grade.
Frequently Asked Questions
What Curie temperature range is shown for the listed AlNiCo grades?
The technical table lists Curie temperature values from 810°C to 860°C for grades where TC data is provided. Individual grades differ, so buyers should use the grade-specific value rather than treating all AlNiCo grades as having the same Curie temperature.
Is Curie temperature the same as the stated maximum operating temperature?
No. The product page presents Curie temperature and maximum operating temperature as separate characteristics. The technical table lists Curie temperatures of 810–860°C for grades with TC data, while the product description separately states that AlNiCo magnets have a maximum operating temperature exceeding 400°C.
Why does grade selection matter when temperature performance is important?
The listed AlNiCo grades differ not only in Curie temperature but also in remanence, coercive force, maximum energy product, and temperature coefficient data. Engineers should therefore compare the complete set of grade-specific magnetic and temperature characteristics instead of selecting a grade from Curie temperature alone.