Fe-Cr-Co (FCC) Cast & Rolled Rare-Earth-Free Permanent Magnets

Problem solved

Manufacturers of sensors, stepping motors, and magnetic couplings face volatile pricing and supply risk for rare-earth magnets (NdFeB, SmCo). Ferrite magnets offer low cost but also low magnetic performance. Alnico magnets avoid rare earths but are expensive (high Ni and Co content) and cannot be rolled into thin shapes. Fe-Cr-Co magnets fill the gap: zero rare earths, zero nickel, higher Br than ferrite, and rollable into sheet as thin as ~0.5 mm.

Application contexts

• stepping-motors
• sensors
• solenoids
• torque-limiters
• magnetic-clamps
• magnetic-couplings
• reed-switches

Technical principle

Fe-Cr-Co magnets derive their permanent magnetism from spinodal decomposition: a homogeneous Fe-Cr-Co solid solution is heat-treated to separate into two phases — an iron-rich ferromagnetic phase and a chromium-rich weakly magnetic phase — forming a fine rod-like microstructure that pins magnetic domain walls. The magnet can be further strengthened by cold or hot rolling, which refines the spinodal structure and enables sheet thicknesses impossible with casting. Unlike sintered magnets, FCC magnets can be machined, punched, bent, and deep-drawn after heat treatment.

Typical use cases

• Stepping motor rotors for industrial automation and CNC machines requiring consistent torque without rare-earth volatility
• Magnetic position sensors in automotive throttle and brake systems where reliable operation up to 300°C is required
• Solenoid actuators for pneumatic and hydraulic valves where moderate magnetic force is sufficient
• Torque limiters in power tools and exercise equipment using FCC magnet's moderate coercivity for easy magnetic reversal
• Magnetic clamps for workholding in machine tools