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Abstract Nanotwins (NTs) significantly enhance strength and thermal stability of face-centered cubic (FCC) alloys compared to coarse-grained counterparts. However, alloying elements can affect NT stability at elevated temperatures. We combined molecular dynamics (MD) simulations with a recently developed anisotropic multi-phase phase field model to investigate NT stability in two Ni-based binary alloys: Ni–Cr and Ni–Fe. MD simulations reveal Ni–Fe alloys have higher intrinsic stacking fault energies compared to Ni–Cr alloys across similar solute concentrations. Moreover, solute effects on incoherent twin boundary (ITB) energies differ notably. ITB mobility exhibits Arrhenius behavior within the studied temperature range. Phase field simulations, incorporating MD-derived mobility laws, demonstrate that NT/grain boundary detachment and subsequent detwinning strongly depend on annealing temperature and NT thickness, particularly above 0.4 homologous temperature. These insights aid in designing nanotwinned Ni-based alloys with improved thermal stability and mechanical properties; in particular, additional Cr or Fe content can significantly elevate the onset temperature of NT motion. Graphical abstract
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This content will become publicly available on January 6, 2027
Composition-driven nanotwin engineering in sputtered Ni-Fe and Ni-Cr films: linking fault energetics to twin thickness
In this study, molecular dynamics (MD) simulations are combined with magnetron co-sputtering experiments to examine how Ni-Fe and Ni-Cr compositions affect defect energetics and twin microstructure in thin films. These simulations represent the first direct modeling of nanotwin formation during atomistic deposition. Ensemble MD simulations reveal substantial stochastic variability in grain structure and twin development across deposition runs, yet clear compositional trends emerge. Cr-rich Ni-Cr alloys form dense twin networks with narrow spacing, while Fe-rich Ni-Fe alloys exhibit fewer twins with significantly larger spacing. Scanning transmission electron microscopy (STEM) of Ni-Cr films confirms the predicted high twin density and reduced spacing, validating the link between alloy composition and growth twin formation. Notably, both simulations and experiments reveal that the distribution of twin boundary spacings is log-normal, reflecting the stochastic nature of twin nucleation during deposition. Composition-dependent maps from MD simulations further demonstrate that small variations in Ni-Cr and Ni-Fe chemistry can systematically tune twin boundary formation and enable the design of nanoscale twin architectures. This integrated computational-experimental study establishes a clear inverse relationship between stacking fault energy and average twin spacing, offering a pathway for engineering nanostructured coatings with tailored twin networks and enhanced properties.
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- Award ID(s):
- 2323936
- PAR ID:
- 10712932
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Acta Materialia
- Volume:
- 306
- Issue:
- C
- ISSN:
- 1359-6454
- Page Range / eLocation ID:
- 121890
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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