Effect of niobium on microstructure and magnetic properties of bulk anisotropic NdFeB/α-Fe nanocomposites

► Nb has great influence on the microstructure and magnetic properties of (NdDy)11.5Fe82.4−xNbxB6.1 (x=0-2.0) nanocomposites. ► Most of Nb atoms gather in the grain boundary to form Nb-rich amorphous intergranular phase, not NbFeB boride. ► Furthermore, grain alignment can be prompt by the Nb-rich solid intergranular phase during deform. ► Remanence, coercivity and (BH)m of deformed (NdDy)11.5Fe80.4Nb2B6.1 nanocomposite is 1.04T, 563 kA/m and 146 kJ/m3 respectively. ► This study provides an alternative method for prepare anisotropic nanocomposite direct from Nd-lean alloys with low cost.