SamariumCobalt

Samarium–cobalt magnets, often written as samarium-cobalt or SmCo magnets, are a family of permanent magnets composed mainly of samarium and cobalt. They were among the first commercially important rare-earth magnets, developed in the 1960s, and exist mainly in two alloy systems: SmCo5 and Sm2Co17. These magnets are produced by casting or arc melting followed by powder metallurgy and sintering, though SmCo5 has historically been produced by casting and subsequent machining.

SmCo magnets are valued for high energy products and exceptional resistance to demagnetization. They also exhibit excellent high-temperature stability, maintaining significant magnetization where many magnets falter. Typical operating temperatures for standard grades reach about 180–250°C, with high-temperature variants rated up to around 300–350°C. Corrosion resistance is good, and in many environments SmCo magnets do not require protective coatings, though mechanical shock and humidity can influence performance. They are relatively brittle and can be susceptible to thermal shock.

The SmCo5 family offers solid coercivity and moderate energy density, while Sm2Co17 delivers higher energy products. Processing challenges include precise alloy composition control and high-temperature sintering to prevent phase decomposition and preserve magnetic properties.

Applications span aerospace actuators, precision instruments, high-temperature motors, wind-turbine components, and medical devices where stable magnetism at elevated temperatures is essential. Because samarium and cobalt are relatively expensive and subject to supply constraints, SmCo magnets are favored for demanding, high-temperature or precision applications where alternatives such as NdFeB may not suffice.