FeGa

FeGa, commonly called Galfenol, is an iron–gallium alloy that combines ferromagnetism with magnetostriction. It is produced by alloying iron with a small percentage of gallium, typically in the range of about 15 to 25 atomic percent Ga, though higher Ga contents are used to tailor the magnetostrictive response. The material is valued for its large, reversible magnetostriction at room temperature and for its mechanical ductility relative to other magnetostrictive alloys.

Properties: FeGa shows relatively high magnetic permeability, low coercivity, and magnetostriction in the hundreds of parts per million range under practical magnetic fields. The performance depends strongly on composition, thermal treatment, and mechanical processing. Proper annealing and controlled cold work can improve magnetostriction, reduce hysteresis, and stabilize properties. The alloy is generally machinable and weldable, enabling fabrication of complex components.

Production and processing: FeGa is produced by conventional metallurgical methods, such as arc or induction melting, followed by casting and thermo-mechanical processing (rolling, drawing, and annealing). Heat treatment can tailor the microstructure to optimize magnetostrictive response and magnetic softness.

Applications: The combination of appreciable magnetostriction, ductility, and processability makes FeGa suitable for magnetostrictive sensors and actuators, acoustic devices, energy harvesting, and microelectromechanical systems components. It is used in precision positioners, valve actuators, and vibration damping systems where a solid-state transducer is advantageous.

History: Galfenol was developed in the late 1990s by researchers at the Naval Research Laboratory and affiliated institutions. The name derives from iron (Fe) and gallium (Ga).