Structural-Phase Transformations in Stainless Steel CF8 Under Ion Implantation and Thermal Treatment

The γ ⟶ α'-transformation under implantation of austenitic-ferritic steel CF8 with ⁵⁷Fe ions to fluences of 1 × 10¹⁶, 5 × 10¹⁶ and 1 × 10¹⁷ ion/cm², as well as the reverse α' ⟶ γ-transformation under thermal treatment, was studied using transmission Mössbauer spectroscopy (MS), conversion electron Mössbauer spectroscopy (CEMS), and X-ray diffraction (XRD) methods. It was found that implantation, which causes radiation damage with 36 dpa, results in the formation of α'-martensite. At higher fluences of implanted ions, the amount of α'-martensite increased, reaching 86 at.% within the irradiated layer. Annealing in the temperature range of 600-850 °C resulted in the observed reverse transformation of α'-martensite to γ-austenite. The dependence of the average effective magnetic field on the annealing temperature was established.