EFI Alloy 50 Applications

A Specialized, Soft Magnetic Alloy for Your Next Application

EFI Alloy 50 is found in applications that require extremely high permeability at low magnetizing forces.  The alloy greatly increases the efficiency and performance of magnetic devices, such as laminated cores for instrument transformers, magnetic shields and cores.

Due to its characteristic high permeability, EFI Alloy 50 has also been used in solenoid cores and sensitive relays that must respond to low magnetizing forces.

Examples of typical applications utilizing EFI Alloy 50:

  • LF power transducers
  • Rotor and stator laminations
  • Chokes
  • Relay parts
  • Integrating current transformers for earth-leakage circuit breakers
  • Stepping motors
  • Magnetic valves
  • Shielding

The magnetic properties of EFI Alloy 50 (also known as High Permeability 49®, Magnifer® 50 or 4750 Alloy) require specific and specialized final heat treating to achieve the maximum magnetic performance.

For more information on technology, engineering and advanced materials applications, you can visit the IEEE website, one of the largest technical professional organizations worldwide.


Suggested final annealing for obtaining optimum magnetic properties:

  • Optimal magnetic properties are obtainable only after a special final annealing treatment. Annealing must take place in dry hydrogen (dew point < -40 °C) or vacuum. These properties are influenced by the configuration of the furnace and the heat mass being processed.
  • The recommended annealing temperature for EFI Alloy 50 is between 1050 and 1250 °C, with an annealing time of 2 to 8 hours. The parts must be furnace-cooled at a rate of 38 – 93°C per hour to about 450 °C. The cool down rate has an influence on the magnetic performance and should be adjusted per application.
  • After the final heat treatment, the parts must not be subjected to further mechanical stress, as any plastic deformation results in a considerable loss of magnetic properties.