AlNiCo

AlNiCo is one of the oldest magnetic materials still available having been developed during and just after the Second World War. Given its early development it is no surprise that AlNiCo is one of the lowest energy product materials available and has one of the highest cost to energy ratios.

AlNiCo is normally an anisotropic material which results in order to get the maximum amount of energy per unit cost from the material but can also be found in isotropic forms and compression bonded in epoxy resin. Two main variants are normally used in industrial applications AlNiCo 5 and AlNICo 8.

AlNiCo 5 has less cobalt than AlNiCo 8 and thus has a higher remenance but a lower coercivity. The loop is generally quite square and the material should be used in applications with a load-line cutting the demagnetisation curve above the knee.

AlNiCo 8 has more cobalt than AlNiCo 5 and thus has a lower remenance and a higher coercivity. The curve is much less square and is a continuous function with no discernable knee. As such applications in AlNiCo 8 are less sensitive to the design of the magnetic circuit.

The main interest in AlNICo in the current world market is its ability to be de-magnetised in a controlled fashion and also its very good temperature performance.

As the material has a very low coercivity when compared to other permanent magnets AlNiCo can be demagnetised by small amounts thus allowing for a calibration of a magnet or system to a specific field value. This is of specific importance in areas such as instrumentation were defined values are so important.

The excellent temperature coefficients of AlNiCo mean that it can be used in high temperature applications were ferrite or NdFeB cannot be used.