Examination of hydrogen embrittlement in FeAl by means of in situ electrochemical micropillar compression and nanoindentation techniques

The hydrogen effect on dislocation nucleation in FeAl single crystal with (100) surface orientation has been examined with the aid of a specifically designed nanoindentation setup for in situ electrochemical experiments. The same setup with the aid of a flat punch tip was used to perform micropillar compression tests. The micropillars were cut by using a focused ion beam system. The effect of the electrochemical potential on the indent load-displacement curve and pillar stress strain 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 experiments due to in situ hydrogen charging. Clear evidence is provided that hydrogen atoms facilitate homogenous dislocation nucleation.