Quantification of dislocation nucleation stress in TiN through high-resolution in situ indentation experiments and first principles calculations

Through in situ indentation of TiN in a high-resolution transmission electron microscope, the nucleation of full as well as partial dislocations has been observed from {001} and {111} surfaces, respectively. The critical elastic strains associated with the nucleation of the dislocations were analyzed from the recorded atomic displacements, and the nucleation stresses corresponding to the measured critical strains were computed using density functional theory. The resolved shear stress was estimated to be 13.8 GPa for the partial dislocation 1/6 <110> {111} and 6.7 GPa for the full dislocation 1/2 <110> {110}. Such an approach of quantifying nucleation stresses for defects via in situ high-resolution experiment coupled with density functional theory calculation may be applied to other unit processes.