Properties of a rare earth free L1 ₀ -FeNi hard magnet developed through annealing of FeNiPC amorphous ribbons

The rare-earth-free hard magnetic L1 ₀ -FeNi phase found in cosmic meteorites demonstrates potential as a next-generation permanent magnet. However, it is very difficult to artificially produce the L1 ₀ -FeNi phase due to the low atomic diffusion coefficients of Fe and Ni near the order-disorder transition temperature (∼320 °C). Therefore, FeNiPC amorphous alloy systems exhibiting crystallization temperature (T _x ) near the transition temperature were investigated. The amorphous alloys were annealed at T _x , resulting in high atomic diffusion. The structural and microstructural characterizations of annealed ribbons revealed the formation of L1 ₀ -FeNi phase through observation of the superlattice peak. The magnetic property, such as coercivity (H _c ), also indicated the formation of L1 ₀ -FeNi phase, because the maximum H _c value is 641 Oe after the annealing process.