AlNiCo is the earliest developed permanent magnet material, which is an alloy of aluminum, nickel, cobalt, iron and other trace metals. Alnico permanent magnet material was developed in the 1930s. At that time, its best magnetic properties, temperature coefficient and small, so the most widely used in the permanent magnet motor. Since the 1960s, with the advent of ferrite magnets and rare earth permanent magnets, the application of AlNiCo magnets in electric motors has gradually been replaced and the proportion of them has been declining.
According to the different production process is divided into Sintered AlNiCo (Sintered AlNiCo) and cast AlNiCo (Cast AlNiCo). Product shapes and more round and square shape. The casting process can be machined to different sizes and shapes; the sintered product is confined to a smaller size than the casting process, producing a better dimensional tolerance of the blank than the cast product, with slightly lower magnetic properties than the cast product, but Processing is better. In permanent magnetic materials, cast aluminum nickel-cobalt permanent magnet has the lowest reversible temperature coefficient, the working temperature can be as high as 600 degrees Celsius. Alnico permanent magnet products are widely used in various instrumentation and other applications.
Alnico magnets have the advantage of remanence magnetism (up to 1.35T) with a low temperature coefficient. The temperature coefficient of -0.02% / ℃, the maximum temperature up to 520 ℃. The disadvantage is that the coercivity is very low (typically less than 160 kA / m) and the demagnetization curve is non-linear. Therefore, alnico magnet although easy to be magnetized, it is also easy to demagnetization.