About this Abstract |
Meeting |
2020 TMS Annual Meeting & Exhibition
|
Symposium
|
Fatigue in Materials: Fundamentals, Multiscale Characterizations and Computational Modeling
|
Presentation Title |
Atomistic and Dislocation Dynamics Simulations of The Interaction of Dislocations with Twin Boundaries in FCC Alloys |
Author(s) |
Satish I. Rao, Maxime Dupraz, Jafaar El-Awady, Christopher Woodward |
On-Site Speaker (Planned) |
Satish I. Rao |
Abstract Scope |
Annealing twins in polycrystalline Ni-based alloys produce stress concentrations during cyclic loading. Sub-grain digital image correlation of these boundaries under load show a factor of 4-10 local strain enhancement. A detailed understanding of the 3D dislocation-twin boundary interactions is required before dislocation dynamics simulations can be used to study this behavior. 3D atomistic simulations are used to study the interaction of screw dislocations with twin boundaries in Cu, Ni and Ni-12.5Al bipillars. The screw dislocation overcomes the low angle twin boundary at fairly low stresses by cross-slip in Cu, Ni and increases for Ni-12.5Al. Results are interpreted using a newly developed cross-slip model based on Escaig’s mechanism . Results of preliminary atomistically informed dislocation dynamics simulations on local strain enhancement in the gamma-matrix of superalloys near twin boundaries during cyclic loading is presented. These results are then used to explain fatigue crack nucleation in Ni based superalloys. |
Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |