Application of a nano-incremental step loading (N-ISL) in a Ni-base superalloy under a hydrogen charging environment

This study proposes the use of a loading profile based on a combination of the ISL technique and the continuous multicycle indentation. This combination in our study was named N-ISL loading profile. The N-ISL loading profile was used to evaluate the hydrogen effect on nanomechanical properties of a Ni-base superalloy single crystal. For this purpose, nanoindentations were performed on a single crystal Ni-base superalloy. Hydrogen charging was carried out by cathodic protection with the sample immersed in a NaCl 3.5 wt% aqueous solution under a current density of − 1 mA/cm 2 . The results showed that the modified N-ISL profile provided the required time for hydrogen accumulation under the indenter tip, enhancing the hydrogen effect. The load relief in the N-ISL profile was found to be the major indicator of plastic deformation event and consequently strong evidence of dislocation movement. The hydrogen charging accentuated the plastic deformation in all steps, indicating that the hydrogen affected the dislocation mobility. Graphical abstract