Disconnection-Mediated Transition in Segregation Structures at Twin Boundaries
Chongze Hu1, Douglas L Medlin2, Rémi Dingreville1
1Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
The Journal of Physical Chemistry Letters
|July 19, 2021
Summary
Gold-doped platinum twin boundaries exhibit unusual atomic segregation. Disconnections with stacking faults drive a transition from bilayer to trilayer segregation structures, impacting material properties.
Area of Science:
- Materials Science
- Nanomaterials
- Physical Chemistry
Background:
- Twin boundaries are crucial for nanocrystalline metal properties.
- Atomic-scale understanding of twin boundaries guides material fabrication.
- Interfacial structure dictates material thermodynamics, stability, and mechanics.
Purpose of the Study:
- To investigate atomic-scale segregation at gold-doped platinum twin boundaries.
- To elucidate the role of disconnections in interfacial segregation phenomena.
- To understand how interfacial defects influence material properties.
Main Methods:
- Atomistic simulations were employed to model atomic structures.
- Structural analysis was performed on simulated interfaces.
- The classical Langmuir-McLean segregation model was applied.
Main Results:
- An unusual segregation phenomenon was observed at gold-doped platinum twin boundaries.
- Disconnections containing stacking faults induced a transition from bilayer to trilayer segregation.
- This transition was observed for faulted disconnections with varying step heights and dislocation characters.
Conclusions:
- Disconnections act as mediators for interfacial segregation at twin boundaries.
- Structurally induced local pressure drops and increased segregation volume drive the observed segregation transition.
- Findings provide insights into controlling interfacial chemistry for enhanced nanocrystalline material properties.
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