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

ABSTRACT

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 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.

KEYWORDS:

• Structural-unit model
• dislocation interaction
• grain boundary
• local stress-fields
• molecular dynamics simulations

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge the support provided by Dr Ali Sayir under the AFOSR Aerospace Materials for Extreme Environment Program (award no. FA9550-15-1-0117), as well as computational time provided by XSEDE (award no. TG-MSS130007) and the Blue Waters sustained-petascale computing project which is supported by the National Science Foundation (awards OCI-0725070 and ACI-1238993) and the state of Illinois.