Study of high-fluence titanium implantation into AISI M2 steel by 48Ti isotopic tracing

AISI M2 steel was implanted with titanium ions of 110 keV incident energy at room temperature. Fluences were varied from 1 to 4x1017 Ti cm-2. The 48Ti(p, γ)49V resonant nuclear reaction at 1362 keV was used to determine selectively the 48Ti distribution profiles. The γ-rays of 7.936 MeV energy and the related escape peaks were identified and used to quantify the 1362 keV resonance yield. In order to understand the mechanisms taking place during titanium implantation, a high Ti fluence was implanted in several steps made up of, first, a 101748Ti cm-2 dose, followed by several successive 101746Ti cm-2 doses. Thus the evolution of the initially implanted 48Ti distribution was followed as the 46Ti dose increased. On the basis of the experimental results, a primary recoil mixing based model is proposed. The agreement obtained between experimental and theoretical mixing rates suggests that the primary recoil mixing process and the sputtering effect are the most important physical mechanisms during high-fluence Ti implantation into steels. (orig.)