<p>A series of amorphous Fe_73.5Cu₁Nb₃Si_{17.5−<i>x</i>}Al_<i>x</i>B₅ (<i>x</i> = 0.2, 0.4, 0.6) alloys were prepared via single-roller melt spinning technology, and their crystallization processes were systematically analyzed. Differential scanning calorimetry results reveal that the onset temperature of primary crystallization, corresponding to the precipitation of the soft magnetic crystalline phase, decreases with increasing Al content, whereas the secondary crystallization onset temperature, associated with the precipitation of the hard magnetic crystalline phase, increases. The addition of Al broadens the temperature range suitable for forming dual-phase nanocrystalline soft magnetic alloys. Analysis of Kissinger plots indicates that the energy barrier required for nucleation in amorphous alloys gradually decreases with Al doping, enabling crystallization to occur at lower temperatures. The sample with <i>x</i> = 0.6 has the highest saturation magnetization and magnetic permeability due to its larger crystalline phase volume fraction.</p>