The epitaxial growth of FeSi2 silicides was studied by using ion‐beam epitaxial crystallization (IBIEC) of Fe‐implanted Si(001) samples. By employing Rutherford backscattering/channeling spectrometry and transmission electron microscopy it was possible to determine that the IBIEC process produces a γ‐, α‐, and β‐FeSi2 phase sequence, with increasing Fe concentration along the implantation profile. The critical concentrations for γ→α and α→β phase transitions are 11 and 21 at. %, respectively. A study of the thermal behavior of these phases shows that the γ‐ and α‐FeSi2 are metastable with respect to the β‐FeSi2 phase. The γ to β‐FeSi2 transition starts at 700 °C via an Ostwald ripening process. In addition a 800 °C, 1 h anneal of high Fe concentration samples produces a complete α and γ to β‐FeSi2 transformation. Finally, it is demonstrated that a regular or a rapid thermal annealing on Fe‐implanted Si samples induces only the formation of a β‐FeSi2 phase. © 1996 American Institute of Physics.