Electronmicroscopical Study of the Formation of Iron Carbide Phases After High-fluence Carbon Ion Implantation into Iron at Low Temperatures

Abstract

Carbon ions were implanted with energies between 50 and 150 keV into thin iron layers at temperatures of –10 °C and –70 °C. Formation of iron carbide phases was studied as a function of fluence, which was varied from 1.2 × 1017 C+-ions/cm2 up to 1.4 × 1018 C+-ions/cm2. The sequence of phase transformation during subsequent annealing to temperatures of up to 450 °C was also investigated. Detailed analysis of structure and morphology was done by cross-sectional transmission electron microscopy and electron diffraction experiments. The existence of metastable iron carbide phases, θ-Fe3C, Χ-Fe5C2, η-Fe2C, and also the amorphous phase Fe(C), after high-fluence carbon ion implantation and the transformation of the formed metastable phases by subsequent annealing into the θ-Fe3C phase are demonstrated.