Discovered independently in 1984 by General Motors (melt-spun nanocrystalline ribbons) and Sumitomo Special Metals (Masato Sagawa's sintered blocks), Nd2Fe14B is the strongest commercially available permanent magnet.
Strong uniaxial magnetocrystalline anisotropy (~7 T) in its tetragonal lattice and four unpaired 4f electrons per Nd atom yield remanence of 1.0–1.5 T and energy density up to 18 times that of ferrite magnets by volume.
Because coercivity drops above 100 °C toward its 310–370 °C Curie temperature and sintered grains corrode readily, electric-vehicle traction motors and wind-turbine generators alloy in dysprosium or terbium and plate parts with Ni-Cu-Ni.