The effect of milling time on the microstructural evolution and magnetic properties of a new Fe-based amorphous/nanocrystalline powder produced via mechanical alloying (MA) has been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). The Rietveld refined XRD results show that the weight fraction of the amorphous phase increases to about 94% after 120 h of milling and then decreases to about 89% by further milling to 150 h due to partial crystallization. The contribution of lattice strain to solid-state amorphization has been discussed in the frame work of the Egami's topological instability model. The DSC measurements demonstrate that the obtained glassy powders after 120 h of milling have a high thermal stability, according to their wide supercooled liquid region of 75 K. The magnetic measurements indicate that saturation magnetization decreases continuously up to 50 h and then slightly increases after 150 h of milling. Simultaneously, magnetic coercivity rapidly increases and then notably decreases with the milling process. In addition, it has been shown that an annealing treatment at 673 K can significantly improve the soft magnetic properties of 120 h milled powders through the reduction of coercivity from 2.72 kA/m to 138 kA/m. (C) 2017 Elsevier B.V. All rights reserved.