About this Abstract |
Meeting |
2022 TMS Annual Meeting & Exhibition
|
Symposium
|
Computational Thermodynamics and Kinetics
|
Presentation Title |
Entropic Effects on Thermally Activated Dislocation Cross-slip |
Author(s) |
Yifan Wang, Wei Cai |
On-Site Speaker (Planned) |
Yifan Wang |
Abstract Scope |
Dislocation cross-slip is one of the main microscale mechanisms involved in the temperature dependence of stage-III strain-hardening of face-cubic centered (fcc) metals. So far, atomistic investigations of cross-slip rate focused on determining the activation enthalpy of cross-slip under stress and the entropic effects were usually neglected. We show that the rate predicted based only on activation enthalpy underestimates the cross-slip rate by 6-orders of magnitude compared to direct molecular dynamics (MD) simulation. Based on harmonic transition state theory (HTST) with corrections of anharmonic soft modes, we develop a fully atomistic model that successfully predicts the cross-slip rate of fcc nickel under a much wider range of stress and temperature conditions. We find that thermal expansion and thermal softening effects contribute significantly to the activation entropy and the rate due to a non-negligible coupling between the activation enthalpy to the hydrostatic component of the stress. |
Proceedings Inclusion? |
Planned: |
Keywords |
Modeling and Simulation, Mechanical Properties, Copper / Nickel / Cobalt |