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Anisotropic Compositional Expansion And Chemical Potential For Amorphous Lithiated Silicon Under Stress Tensor, Valery I. Levitas, Hamed Attariani
Anisotropic Compositional Expansion And Chemical Potential For Amorphous Lithiated Silicon Under Stress Tensor, Valery I. Levitas, Hamed Attariani
Mechanical and Materials Engineering Faculty Publications
Si is a promising anode material for Li-ion batteries, since it absorbs large amounts of Li. However, insertion of Li leads to 334% of volumetric expansion, huge stresses, and fracture; it can be suppressed by utilizing nanoscale anode structures. Continuum approaches to stress relaxation in LixSi, based on plasticity theory, are unrealistic, because the yield strength of LixSi is much higher than the generated stresses. Here, we suggest that stress relaxation is due to anisotropic (tensorial) compositional straining that occurs during insertion-extraction at any deviatoric stresses. Developed theory describes known experimental and atomistic simulation …
Effect Of Process Variables On Sub-Melt Thermal Behavior And Solid-State Phase Transformations In Beam-Based Additive Manufacturing Of Ti-6al-4v, Heather N. Doak
Effect Of Process Variables On Sub-Melt Thermal Behavior And Solid-State Phase Transformations In Beam-Based Additive Manufacturing Of Ti-6al-4v, Heather N. Doak
Browse all Theses and Dissertations
The success of laser and electron beam-based fabrication processes for additive manufacture and repair applications requires the ability to control melt pool geometry while maintaining a consistent and desirable microstructure. Previous work has employed a process map approach to link melt pool geometry to solidification microstructure (grain-size and morphology) in beam-based fabrication of Ti-6Al-4V. The current work extends the approach to investigate the effects of process variables on solid-state phase transformations below the solidification temperature through Finite Element Modeling, the 3-D Rosenthal Solution, and experimentation. Process maps for solid-state microstructure could be used to help maintain consistent and reliable mechanical …