High coercivity Nd2Fe14B/α-Fe nanocomposite magnets

High coercivity Nd2Fe14B/α-Fe nanocomposite magnets have been prepared with the addition of 5% Nb elements. The amorphous formation ability and thermal stability of as-spun ribbons were increased. A fine and uniform microstructure with 10 nm was achieved after the ribbons with normal composition (Nd0.9Dy0.1)9.5Fe74Co5Nb5B6.5 were annealed at 710 °C for 4 min, which enhances the interaction coupling between grains and improves the coercivity greatly. The results of three-dimensional atom probe (3DAP) revealed that Nb–Fe–B intergranular phase with the ratio of Nb:Fe:B=1:1:1 existed at the boundary of grains, suppressing the grain growth during crystallization process. The coercivity of ribbons with 5at% Nb elements reaches to 1115 kA/m, which is the much higher value for the ribbons with 9.5at% total rare earth for Nd2Fe14B/α-Fe nanocomposite magnets.