Exchange-coupled nanoscale SmCo/NdFeB hybrid magnets

► We realize interphase exchange coupling in nanoscale SmCo5/Nd2Fe14B magnets. ► We observe homogenously distributed two-phase grains with size smaller than 20 nm. ► We observe a common Curie temperature in the hybrid magnet. ► High-temperature magnetic properties of the hybrid magnets greatly improved. ► Plastic deformation of composite materials leads to self-nanoscaling of grains.