Cyclic and tensile deformations of Gold-Silver core shell systems using newly parameterized MEAM potential

SMAA Alvi and A Faiyad and MAM Munshi and M Motalab and MM Islam and S Saha, MECHANICS OF MATERIALS, 169, 104304 (2022).

DOI: 10.1016/j.mechmat.2022.104304

Gold-Silver (Au-Ag) core-shell nanostructures have significant applicability in stretchable and biocompatible electronics where endurance under high tensile and cyclic loading is a requirement. This work, for the first time, quantitatively investigates the role of dislocations and defect interaction governing the mechanical behavior of Au-Ag and Ag-Au Core-shell nanostructures under tensile and cyclic loading using molecular dynamics (MD) simulation. For accurate representation of the underlying physics, a novel modified embedded atomic model (MEAM) interatomic potential for pristine Au, Ag and their alloys is parameterized through two different density functional theory (DFT) schemes. Using the new potential for MD simulations, the cyclic loading properties of pristine and core-shell nanowires (NWs) in a strain range of -15%-15% for 10 cycles are conducted. The tensile behavior of pristine and core-shell NWs is also explored for temperatures between 300 K and 600 K. A comparative analysis between Core-shell structures and their pristine counterparts are carried out. Our results suggest that Ag-Au Core-shell NW exhibit superior stress- strain reversibility under cyclic loading among the structures examined. Ag-Au exhibit the highest dislocation formation and near-complete annihilation of defects consistently. Au-Ag also present improved cyclic loading properties than its pristine counterparts. For tensile loading, all four structures exhibited deterioration in strength with increasing temperature. Thermal softening is observed to be more prominent in Au-Ag core-shell NWs compared to Ag-Au. Our work lays out a foundation for exploration of mechanical properties of Au-Ag systems using the MEAM potential which will help design components for stretchable electronics and creates a pathway for further exploration of similar binary alloy systems.

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