About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
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Grain Boundaries, Interfaces, and Surfaces: Fundamental Structure-Property-Performance Relationships
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| Presentation Title |
Correlative Electron Microscopy of Grain-Boundary Chemistry, Defects, and Strengthening in Metastable Mg–Ti Thin Films |
| Author(s) |
Reza Motallebi, Hyemin Ryu, Gi-Dong Sim, Kelvin Xie |
| On-Site Speaker (Planned) |
Reza Motallebi |
| Abstract Scope |
In metastable alloy thin-films, interfaces govern solute redistribution, defect accommodation, and strengthening mechanisms that are inaccessible under equilibrium processing. Here, we investigate interface structure–chemistry–defect coupling in immiscible Mg–Ti thin-films synthesized by non-equilibrium co-deposition, which stabilizes supersaturated solid solutions beyond equilibrium solubility limits. Using correlative, multimodal transmission electron microscopy—including precession electron diffraction orientation mapping, atomic-resolution TEM/STEM, and STEM-EDS—we quantitatively resolve grain boundary structure, solute segregation, lattice curvature, and defect fields across length scales. Orientation mapping reveals composition-dependent grain refinement and kinetically modified growth fronts, while atomic-scale imaging demonstrates reproducible Ti segregation to grain boundaries without second-phase precipitation. Defect-sensitive imaging links interfacial chemistry to suppressed extended defects and altered lattice distortion. Independent mechanical measurements show that grain-boundary segregation and defect modulation correlate directly with pronounced strengthening. These results establish how non-equilibrium interface thermodynamics and kinetics control microstructural evolution and mechanical response in immiscible structural alloy thin films. |