Aluminum-nickel-cobalt (AlNiCo) is the earliest permanent magnet material developed, which is an alloy composed of aluminum, nickel, cobalt, iron and other trace metal elements. AlNiCo permanent magnet materials were successfully developed in the 1930s. At that time, it had the best magnetic performance and small temperature coefficient, so it was most widely used in permanent magnet motors. After the 1960s, with the successive advent of ferrite permanent magnets and rare earth permanent magnets, the application of AlNiCo permanent magnets in motors was gradually replaced, and the proportion showed a downward trend.
According to different production processes, it is divided into sintered AlNiCo (Sintered AlNiCo) and cast AlNiCo (Cast AlNiCo). The shapes of the products are mostly round and square.
The casting process can be processed into different sizes and shapes; compared with the casting process, the sintered product is limited to small sizes, and the dimensional tolerance of the produced blank is better than that of the cast product. The magnetic properties are slightly lower than the cast product, but can be Processability is better. Among permanent magnet materials, cast AlNiCo permanent magnets have the lowest reversible temperature coefficient, and the working temperature can be as high as 600 degrees Celsius. AlNiCo permanent magnet products are widely used in various instrumentation and other application fields.
The advantages of AlNiCo magnets are high remanence (up to 1.35T) and low temperature coefficient. When the temperature coefficient is -0.02%/℃, the maximum operating temperature can reach about 520℃. The disadvantage is that the coercivity is very low (usually less than 160kA/m) and the demagnetization curve is nonlinear. Therefore, although AlNiCo magnets are easily magnetized, they are also easily demagnetized.