Mechanical Characterization of grain boundary strengthening through TEM in-situ indentation

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TEM in-situ compression test was performed for Fe-Si bicrystal and revealed that dislocations passed through grain boundary without any pile-up. These results suggest that dislocation reaction occurs at grain boundary. We observed two types of dislocations of screw and edge during deformation. Load-displacement curves obtained with TEM observation shows that screw type dominant with lower mobility corresponds to higher flow stress. Another data shows obvious yield phenomenon and subsequently remarkable strain softening. In that case, dislocation density increases with strain after yielding. For the quantitative relationship between the flow stress and dislocation density is understood in the Johnston Gilman model