Partial dislocations interactions with symmetrical-tilt grain boundaries containing e-structural units: Local stress analysis with molecular dynamics

Mohan, Sivasakthya

Permalink

https://hdl.handle.net/2142/101206 Copy

Description

Title

Partial dislocations interactions with symmetrical-tilt grain boundaries containing e-structural units: Local stress analysis with molecular dynamics

Author(s)

Mohan, Sivasakthya

Issue Date

2018-04-24

Director of Research (if dissertation) or Advisor (if thesis)

Chew, Huck Beng

Department of Study

Aerospace Engineering

Discipline

Aerospace Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Date of Ingest

2018-09-04T20:36:50Z

Keyword(s)

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

Abstract

Grain boundaries containing porous E-structural units (SUs) are known to readily emit dislocations under tension. This work establishes a correlation between the atomic structure, evolution of interfacial stresses and slip transfer mechanisms at grain boundaries containing E-structural units. 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 site. For the favored Σ9(221) grain boundary comprising only of E-SUs, Shockley partials originating from E-SUs located within the tensile stress regime are subsequently re-emitted into the neighboring 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 partial can also be transmitted through the boundary or be stably absorbed by the boundary with no subsequent re-emission, depending on the impingement site.

Graduation Semester

2018-05

Type of Resource

text

Permalink

http://hdl.handle.net/2142/101206

Copyright and License Information

Copyright 2018 Sivasakthya Mohan

Owning Collections