Hydrogen permeation behavior in pure nickel implanted with phosphorus, sulphur and their mixture

The entry and transport of hydrogen in phosphorus (P)-, sulphur (S)- and their mixture (P + S)-implanted nickel specimens with a fluence range of 1 × 1015 to 1 × 1017/cm2 have been investigated using an electrochemical permeation technique and etching treatment (0.2% HF solution). From the hydrogen permeation transients obtained, the effective hydrogen concentration (CH), apparent hydrogen diffusion coefficient (Dlag) and breakthrough time (tlag) were estimated by using the time lag method in addition to the steady state permeation current density (P∞). It was found that at a fluence of less than 1 × 1016/cm2 almost all hydrogen permeation transients of the implanted nickel specimens were affected by the defects (vacancy, compressive stress and so on) generated during ion implantation process. At a high fluence of 1 × 1017/cm2 the hydrogen permeation transient had a specific behavior because of the formation of amorphous phase for P, the structure change from fcc-structure to bcc-structure for S and both of them for the mixture (P and S). However, a synergistic effect of P and S was not observed on the hydrogen permeation transient. The behavior of these parameters depending on fluence and implanting element was discussed in terms of an amount of hydrogen entry site, the degree of defects, the properties of amorphous phase and structure and so on.