The hydrogen effect upon dislocation nucleation in FeAl single crystal with (100) surface orientation was examined with the aid of a specifically designed nano-indentation setup for in situ electrochemical experiments. The effect of the electrochemical potential upon the indent load–displacement curve, especially the unstable elastic-plastic transition (pop-in), was studied in detail. The observations showed a reduction in the pop-in load for both samples due to in situ hydrogen charging, which was reproducibly observed within sequential hydrogen charging and discharging. Clear evidence was provided that hydrogen atoms facilitate homogeneous dislocation nucleation.

In situ Electrochemical Nanoindentation of FeAl (100) Single Crystal - Hydrogen Effect on Dislocation Nucleation. A.Barnoush, C.Bies, H.Vehoff:  Journal of Materials Research, 2009, 24[3], 1105-13