Influence of alloying elements on mechanical properties and microstructures of sintered Nd-Fe-Co-B magnet

Abstract Elements Cu and Nb were added into the sintered Nd–Fe–Co–B magnet in order to improve the mechanical properties of the magnet. The bending strength of the magnet increased at low level (⩽1 at%) of Cu or Nb additions while the fracture toughness slightly increased for Nb and decreased for Cu addition. The fracture mode of the magnet was still brittle failure. The microstructures of these magnets were investigated with the emphasis on the relationship between mechanical properties and microstructure using optical microscopy, SEM and EDX. New phases were found in the magnets. The reason why the mechanical properties of the magnets were improved is also discussed.