skip to main content

DOE PAGESDOE PAGES

Title: Mechanochemical spinodal decomposition: a phenomenological theory of phase transformations in multi-component, crystalline solids

Here, we present a phenomenological treatment of diffusion-driven martensitic phase transformations in multi-component crystalline solids that arise from non-convex free energies in mechanical and chemical variables. The treatment describes diffusional phase transformations that are accompanied by symmetry-breaking structural changes of the crystal unit cell and reveals the importance of a mechanochemical spinodal, defined as the region in strain-composition space, where the free-energy density function is non-convex. The approach is relevant to phase transformations wherein the structural order parameters can be expressed as linear combinations of strains relative to a high-symmetry reference crystal. The governing equations describing mechanochemical spinodal decomposition are variationally derived from a free-energy density function that accounts for interfacial energy via gradients of the rapidly varying strain and composition fields. A robust computational framework for treating the coupled, higher-order diffusion and nonlinear strain gradient elasticity problems is presented. Because the local strains in an inhomogeneous, transforming microstructure can be finite, the elasticity problem must account for geometric nonlinearity. An evaluation of available experimental phase diagrams and first-principles free energies suggests that mechanochemical spinodal decomposition should occur in metal hydrides such as ZrH 2-2c. The rich physics that ensues is explored in several numerical examples in two and threemore » dimensions, and the relevance of the mechanism is discussed in the context of important electrode materials for Li-ion batteries and high-temperature ceramics.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Mechanical Engineering
  2. Univ. of California, Santa Barbara, CA (United States). Dept. of Materials
  3. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Mechanical Engineering and Dept. of Mathematics
Publication Date:
Grant/Contract Number:
SC0008637; CHE1027729; DMR 1105672
Type:
Accepted Manuscript
Journal Name:
npj Computational Materials
Additional Journal Information:
Journal Volume: 2; Journal Issue: 1; Journal ID: ISSN 2057-3960
Publisher:
Nature Publishing Group
Research Org:
Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; batteries; computational methods; mechanical properties; metals and alloys
OSTI Identifier:
1438027

Rudraraju, Shiva, Van der Ven, Anton, and Garikipati, Krishna. Mechanochemical spinodal decomposition: a phenomenological theory of phase transformations in multi-component, crystalline solids. United States: N. p., Web. doi:10.1038/npjcompumats.2016.12.
Rudraraju, Shiva, Van der Ven, Anton, & Garikipati, Krishna. Mechanochemical spinodal decomposition: a phenomenological theory of phase transformations in multi-component, crystalline solids. United States. doi:10.1038/npjcompumats.2016.12.
Rudraraju, Shiva, Van der Ven, Anton, and Garikipati, Krishna. 2016. "Mechanochemical spinodal decomposition: a phenomenological theory of phase transformations in multi-component, crystalline solids". United States. doi:10.1038/npjcompumats.2016.12. https://www.osti.gov/servlets/purl/1438027.
@article{osti_1438027,
title = {Mechanochemical spinodal decomposition: a phenomenological theory of phase transformations in multi-component, crystalline solids},
author = {Rudraraju, Shiva and Van der Ven, Anton and Garikipati, Krishna},
abstractNote = {Here, we present a phenomenological treatment of diffusion-driven martensitic phase transformations in multi-component crystalline solids that arise from non-convex free energies in mechanical and chemical variables. The treatment describes diffusional phase transformations that are accompanied by symmetry-breaking structural changes of the crystal unit cell and reveals the importance of a mechanochemical spinodal, defined as the region in strain-composition space, where the free-energy density function is non-convex. The approach is relevant to phase transformations wherein the structural order parameters can be expressed as linear combinations of strains relative to a high-symmetry reference crystal. The governing equations describing mechanochemical spinodal decomposition are variationally derived from a free-energy density function that accounts for interfacial energy via gradients of the rapidly varying strain and composition fields. A robust computational framework for treating the coupled, higher-order diffusion and nonlinear strain gradient elasticity problems is presented. Because the local strains in an inhomogeneous, transforming microstructure can be finite, the elasticity problem must account for geometric nonlinearity. An evaluation of available experimental phase diagrams and first-principles free energies suggests that mechanochemical spinodal decomposition should occur in metal hydrides such as ZrH2-2c. The rich physics that ensues is explored in several numerical examples in two and three dimensions, and the relevance of the mechanism is discussed in the context of important electrode materials for Li-ion batteries and high-temperature ceramics.},
doi = {10.1038/npjcompumats.2016.12},
journal = {npj Computational Materials},
number = 1,
volume = 2,
place = {United States},
year = {2016},
month = {6}
}