Magnetic alloys are metallic materials that exhibit strong magnetic properties. They are used in a variety of applications, including electrical motors, generators, and sensors. Magnetic alloys can be made from a wide range of elements, including iron, cobalt, nickel, and rare-earth metals. The specific composition of a magnetic alloy depends on the desired properties. For example, an alloy with a high proportion of iron is often used for permanent magnets, while an alloy with a high proportion of cobalt is often used for electromagnets.
Most magnetic alloys are based on iron. Iron is a relatively inexpensive element and has good magnetic properties. However, iron is also prone to corrosion. As a result, many magnetic alloys contain other elements that improve the resistance to corrosion or enhance the strength of the magnetism. For example, an alloy known as Alnico contains aluminum and nickel. This combination gives the alloy excellent resistance to corrosion while still providing good magnetic properties.
There are two main types of magnetism: ferromagnetism and diamagnetism. Ferromagnetic materials are those that can be permanently magnetized; they have north and south poles like a bar magnet. Diamagnetic materials are weakly attracted to magnets; they do not have north and south poles but instead have opposing north-south poles that cancel each other out (think of how two bar magnets placed end-to-end will repel each other). Most magnetic alloys are ferromagnetic; however, some rare-earth metals such as gadolinium and dysprosium can also be used to create diamagnetic materials with very strong negative polarities (-).