About this Abstract |
| Meeting |
2027 TMS Annual Meeting & Exhibition
|
| Symposium
|
Chemistry and Physics of Interfaces
|
| Presentation Title |
Dislocation-Mediated Kink Boundaries and Their Role in Mechanical Hysteresis in Layered Solids |
| Author(s) |
Seok-Woo Lee, Alexander J Horvath, Sarshad Rommel, Dayoung Lee, Juan Schmidt, Paul C Canfield, Ill Ryu, Mark Aindow |
| On-Site Speaker (Planned) |
Seok-Woo Lee |
| Abstract Scope |
Layered crystals can develop internal interfaces through deformation, via dislocations that organize into kink boundaries. Using CaFe₂As₂, a ThCr₂Si₂-structured intermetallic, we show mechanical hysteresis arises through two distinct routes depending on loading axis. Under c-axis loading, hysteresis stems from a bulk lattice collapse-expansion phase transition with no interface involved. Under a-axis nanoindentation, comparable or larger hysteresis appears despite the absence of this transition. Transmission electron microscopy reveals densely nucleated dislocations self-organizing into inversion-symmetric kink boundary pairs that trap mobile dislocations between them. We performed dislocation dynamics simulations showing these kink boundaries generate a back stress that drives a Bauschinger effect during unloading, with loop area increasing with dislocation density, consistent with experiment. Because geometrically necessary dislocation density scales with strain gradient beneath the indenter, this back stress decreases systematically with depth, producing an indentation size effect. Kink boundaries thus emerge as deformation-induced interfaces that directly control macroscopic mechanical response. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Mechanical Properties, Characterization, Modeling and Simulation |