Local stress analysis of partial dislocation interactions with symmetrical-tilt grain boundaries containing E-structural units

Grain boundaries containing porous E-structural units (SUs) are known to readily emit dislocations under tension. Using molecular dynamics simulations, we study the interactions between <112>{111} Shockley partial dislocations and <110> symmetrical-tilt Ni grain boundaries containing E-SUs. We show that the incoming Shockley partials can be accommodated by porous E-SUs along the grain boundary. However, the partial-absorption process disrupts the short-range interactions of incipient dislocations along the boundary, which generates high local tensile and compressive stress regimes emanating from the impingement sites. For the favoured Sigma 9(221) grain boundary comprising only of E-SUs, incipient Shockley partials originating from E-SUs located within the tensile stress regime are subsequently re-emitted into the neighbouring grain. We demonstrate that the critical strength for re-emission of Shockley partials can be delineated into contributions from tensile stress generated by partial-absorption, intrinsic grain boundary tractions, as well as external loading. In the presence of other types of SUs, the incoming Shockley partials can also be transmitted through the boundary, or be stably absorbed by the boundary with no subsequent re-emission, depending on the impingement site.