The behavior of hydrogen in titanium after ion implantation

Abstract

Ion implantation is a technique which is used to improve tribomechanical behavior of IVb-metals like titanium and its alloys which are interesting materials for a number of technological applications, e.g., in aerospace or in the field of metallic surgical implants. However, ion implantation induces defect formation processes that may influence the hydrogen content and its depth distribution in the implanted material. A large amount of hydrogen accumulation is observed in the implanted near surface region of commercially pure titanium. This effect may have important consequences, since excessive hydrogen accumulation generally leads to precipitating hydrides in the matrix lattice and results in degradation of its mechanical properties. In this contribution, the influence of different implantation parameters on hydrogen accumulation such as the implanted element (B, C, N, O, F, He, Ne and Fe), the ion fluence, sample temperature and residual gas composition was investigated for a better understanding of the observed hydrogen behavior. A correlation between binary phases and hydrogen accumulation was found. Furthermore, it will be discussed whether the hydrogen atoms diffused from the bulk into the modified region or are absorbed from the residual gas in the implantation chamber. The effect of hydrogen accumulation was studied using Nuclear Reaction Analysis (NRA).