Advancing in situ hydrogen embrittlement studies through an integrated charging cell for SEM micromechanical testing

A comprehensive understanding of hydrogen-deformation interactions at the microscale is essential for revealing hydrogen embrittlement mechanisms. In situ micromechanics with simultaneous hydrogen (H-) charging has therefore gained traction in recent times. In the present study, we aim to address the drawbacks of current in situ H-charging setups by developing a more robust 3-electrode-based back-side charging system for a scanning electron microscope to perform various micromechanical tests. The development of the novel setup is discussed and demonstrated through micropillar compression of an Fe-25Cr single crystal (110) during H-charging. H has increased the yield strength and the apparent strain-hardening rate. H activates multiple slip systems and enhances dislocation density and entanglement, leading to pronounced forest hardening as revealed by electron microscopy. Estimation of activation volume from strain-rate jump tests indicates that the deformation is controlled by the solute drag effect on kink mobility and dislocation forest hardening.