Samarium Cobalt

About Samarium Cobalt Magnets

Electron Energy Corporation’s samarium cobalt magnets (SmCo) have been the preferred material of choice since pioneering SmCo production in the 1970s. Because EEC controls every step of the material production from melting of the alloy to machining, we can deliver the highest performance SmCo in the industry. Our SmCo 33 grade of material is the highest performance product available today! SmCo is uniquely fit for high performance applications due to its high energy product (up to 33MGOe), performance across a wide-range range of temperatures (up to 550°C), resistance to corrosion, and resistance to demagnetization.

Key features of sintered SmCo magnets include:

  • Temperature Stability: highest operating temperature of 550°C
  • Resistance to corrosion: highest corrosion resistant rare earth magnet material
  • Highest resistance to demagnetization


  • Motors
  • Generators
  • Actuators
  • Microwave signal amplification
  • Sensors
  • Magnetic field sources
  • Biomedical equipment

Samarium Cobalt Magnetic Properties

Samarium Cobalt Mechanical Properties

Additional Information

SmCo5 Magnets
SmCo5 was developed in the late 1960s and early 1970s. SmCo has a hexagonal crystal structure consisting of five atoms of cobalt for each samarium atom. SmCo5 magnets are also known as RECo5, Sm-Co 1:5, samarium cobalt 1:5 magnets, SmCo series 1:5 magnets, or sometimes simply 1:5 magnets.

SmCo5 has a very high intrinsic coercivity, Hci, which is a measurement of resistance to demagnetization. Its maximum energy product, (BH)max, is about 24 MGOe. The reversible temperature coefficient of residual induction of SmCo5 is about -0.04%/°C. Heavy rare earth elements, such as Gd, Tb, Ho and Er, are sometimes substituted for a portion of the Sm to reduce the reversible temperature coefficient of residual induction.

SmCo5 has very good corrosion resistance and long-term thermal stability. No surface coating is necessary. SmCo5 can be used at temperatures up to 300°C.

Sm2Co17 Magnets
Sm2Co17 was developed in the 1970s. It has a rhombhedral crystal structure, which is obtained by replacing 1/3 of the Sm atoms in the SmCo5 hexagonal structure with a pair of Co atoms known as dumbbells. Commercial Sm2Co17 magnets contain other elements such as iron, copper and zirconium. The partial replacement of cobalt with iron helps increase the saturation magnetization, while the addition of copper and zirconium is critical for the formation of cellular microstructure (see figures below) for the development of high intrinsic coercivity.

[caption id="" align="aligncenter" width="302"] Cellular microstructure of Sm2Co17 type magnets[/caption]


Sm2Co17 is also known as RE2TM17, Sm-Co 2:17, SmCo Series 2:17, Sm(Co,Fe,Cu,Zr)z or sometimes simply 2:17 magnets. Sm2Co17 magnets have very high intrinsic coercivity with maximum energy product (BH)max as high as 34 MGOe. Sm2Co17 magnets can be used at temperatures up to 350°C. The reversible temperature coefficient of residual induction is about -0.035%/°C. Like SmCo5 magnets, heavy rare earth elements can be substituted for a portion of the Sm in order to reduce the reversible temperature coefficient of residual induction for Sm(Co,Fe,Cu,Zr)z magnets.


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