The P content dependences of the crystallization behavior, thermal stability and soft-magnetic properties of high Fe content Fe83.3Si4Cu0.7B12 - xPx (x = 0 to 8) nanocrystalline soft-magnetic alloys were investigated. P addition is very effective in widening the optimum annealing temperature range and refining of bcc-Fe grain size in addition to the increasing of nanocrystalline grain density. Uniform nanocrystalline bcc-Fe grains with average size of about 20 nm and number density of 10(23)-10(24) /m(3) were prepared at around x = 6-8 for the annealed Fe83.3Si4Cu0.7B12 - xPx alloys. The coercivity H-c markedly decreases with increasing x and exhibits a minimum at around x = 6-8, while the saturation magnetic flux density B-s shows a slight decrease. Fe83.3Si4Cu0.7B6P6 nanocrystalline alloy exhibits excellent soft-magnetic properties with a high saturation magnetic flux density B-s of 1.77 T, low coercivity H-c of 4.2 A/m and high effective permeability mu(e) of 11,600 at 1 kHz. (C) 2011 Elsevier B.V. All rights reserved.