AINiCo magnets are a special type of magnet mainly composed of aluminum, nickel, and cobalt. These magnets can also include titanium, iron, and copper. They come in two forms; the isotropic, non-directional form, or the anisotropic, mono-directional form. Once they’re magnetized, they typically have 5 to 17 times the magnetic force of magnetite or lodestone. These are naturally occurring magnets that attract iron. In this post, we’ll talk about the properties, production, and common uses of Alnico magnets.
Before the discovery of rare-earth magnets, AlNiCo magnets were the mainstay of the world of magnets. They used to be the strongest magnets ever known. Even today, they’re still instrumental in several industrial and everyday life applications. AlNiCo magnets are used widely in electric motors, microphones, engineering applications, the aerospace industry, military, sensors, etc. In some cases, they even perform better than the stronger rare-earth magnets.
Generally, they can be produced by either casting or sintering processes. These will be explained in further detail later. They are a combination of three essential elements (Al, Ni, and Co), and have excellent temperature stability, high residual induction, and relatively high energies.
As mentioned earlier in the post, AlNiCo magnets are manufactured in two ways; by sintering or using a casting process. Casting is the more common method because it yields AlNico magnets that are greater in density and mass, and, subsequently, have better magnetic properties and performance. However, sintered AlNico magnets are more economical to produce.
The casting process involves pouring a molten metal alloy into a mold and then further processing it through various heat cycles, which gives a magnet with a dark gray exterior and rough surface. The surface of the magnet can be machined to give a shiny appearance.
In the sintering method, the raw elements are first finely ground by milling them into tiny particles. The powdered magnetic material is pressed under tonnes of pressure in a die that closely resembles the desired magnet shape. After the powder has been pressed, the material is sintered in a furnace in a hydrogen atmosphere at over 1200 degrees Celsius. This process fuses all the pressed particles together to form a single magnet.
The red hot single magnet material is then cooled. If it is cooled in the presence of an external magnetic field, it will have anisotropic properties and a specific magnetic direction. But if it is not cooled in an external magnetic field, the resulting magnet will be isotropic in nature, and without a preferred direction of magnetism.
Further Reading: Cast AlNiCo Magnets Vs. Sintered AlNiCo Magnets
Although AlNiCo magnets have been largely replaced by rare-earth magnets, they are still used for important applications requiring high operating temperatures. This is because they are much more resistant to high temperatures than ferrite or rare-earth magnets.
AlNiCo magnets are often used in the following applications:
AlNiCo magnets are mainly made up of aluminum, nickel, cobalt, and smaller amounts of iron, titanium, and copper. They are one of the strongest known magnets, which can either have a specific direction of magnetic effect or none at all. AlNiCo magnets are often used in high-temperature applications due to their ability to retain their magnetism under high temperatures. If you want to find more about permanent magnets, we would like to recommend you to visit Stanford Magents for more information.