Evidence is presented for pinning controlled coercivity in boron deficient rapidly quenched Fe-Nd-B alloys with additions up to 1.6 at% Nb, In the directly quenched state, the Nb-containing alloy exhibits similar properties to a similar ternary Fe-Nd-B alloy, with enhanced remanence (>0.9 T) and intrinsic coercivity of about 1100 kA m −1. Annealing of overquenched ribbon brings about an increase of the coercivity by up to 30% and a decrease of remanence at a rate of 0.04 T/at% Nb. This phenomenon is associated with precipitation of fine (≈ 5 nm) diameter particles within the hard magnetic phase. These precipitates are considered to create pinning centres for domain wall movement.