AlNiCo Magnets

AlNiCo magnets are permanent magnets based on an alloy of aluminum (Al), nickel (Ni) and cobalt (Co); they are usually supplemented with iron and copper. They offer excellent temperature stability up to 500 °C and high machinability. Although their magnetic strength is lower than that of modern rare earth magnets, they are preferred for measuring instruments, sensors and electromagnetic equipment that require heat resistance, long life and precise field characteristics.

The highest temperature resistance

AlNiCo is the only common permanent magnet family that can operate up to 500 °C. At this temperature neodymium has long since lost its magnetic properties, and SmCo has reached its limit. Its very low temperature coefficient means the field hardly drifts at all with changes in heat — exactly what is wanted in measuring instruments and sensors.

It can be machined

An important point that sets it apart from the other magnet families is its mechanical structure. AlNiCo is a metallic alloy; it is not brittle like a ceramic and is suitable for machining. In applications that require a special geometry, this flexibility makes things considerably easier at the design stage.

Its weak side: demagnetization

The magnetic field of AlNiCo can be disturbed when exposed to a strong external field or to a magnet with opposite polarity. Neodymium and SmCo are much more resistant in this respect. For this reason AlNiCo magnets are positioned carefully in applications with a strong field nearby; if necessary they can be remagnetized.

Where it is used

Measuring instruments, electricity meters, sensors, guitar pickups, holders exposed to heat and older generation motor designs. Although it has given way to rare earth magnets in modern high-power applications, it is still unrivaled when heat stability and machinability are needed together. For a material comparison you can look at the permanent magnets page.