A detailed study of the process of crystallization in amorphous Fe25Sc75, Fe28 Sc72 and Fe25Sc45Zr30 alloys has been carried out using differential scanning calorimetry, X-ray diffraction and Mossbauer spectroscopic techniques. The complex multi-stage transformation process in Fe25Sc75 and Fe28Sc72 is understood in terms of polymorphous formation of an intermediate metastable crystalline phase of orthorhombic structure (a = 0.521 nm, b = 0.648 nm and c = 1.212 nm) and of likely Sc3Fe stoichiometry, before final eutectic crystallization to stable Fe2Sc and α-Sc.