SmCo5/FeCo core/shell composites were fabricated through a magnetic self-assembly process. The core/shell structure was confirmed by TEM image. The effects of the mass percentage of FeCo nanoparticles on the magnetic exchange coupling between SmCo5 and FeCo were investigated. The results showed that a higher mass percentage of FeCo nanoparticles led to a weaker magnetic exchange coupling between SmCo5 and FeCo. The magnetic exchange coupling was beneficial to increase the (BH)(max) of composites. The maximum (BH) max of SmCo5/FeCo composite was obtained when FeCo was 10 wt%, achieving a 25% increase from single hard phase SmCo5. (C) 2018 Elsevier B.V. All rights reserved.