Mechanism of nanostructure formation and magnetic properties in Fe45Co45Ni10 alloy synthesized by high energy milling has been explored in this study. Our results suggested a simultaneous increase in the dislocation density and formation of low-angle grain boundaries when one of the cold welding or fracturing process was predominant (up to 2 h of milling). This was followed by a steady state between cold welding and fracturing (2 to 35 h), which coincided with high angle grain boundaries formation. After milling for 10 h, dissolution of Co and Ni in Fe. correspondingly, resulted in a bcc solid solution. The powders exhibited a minimum grain size of similar to 10 nm and lattice parameter of similar to 0.28512 nm after 35 and 20 h, respectively. Alloy formation enhanced magnetization saturation to about 186 emu/g and grain size refinement decreased coercivity to approximately 32 Oe. (C) 2012 Elsevier B.V. All rights reserved.