Multivariant model of martensitic microstructure in thin films
Resource
Acta Materialia 56 (15): 3969-3981
Journal
Acta Materialia
Journal Volume
56
Journal Issue
15
Pages
3969-3981
Date Issued
2008
Date
2008
Author(s)
Shu, Y. C.
Yen, J. H.
Abstract
A novel multivariant model of martensite is developed through competing energetics to describe the coarsening, refinement and selection of the microstructure. In contrast with the conventional phase-field methods, a new set of field variables motivated by the hierarchical structure of multirank laminates is employed to represent each variant. As a result, the energy-well structure can be expressed explicitly in an elegant and unified fashion. The framework is applied to the investigation of pattern formation in martensitic thin films with trigonal symmetry. Various intriguing patterns are predicted and are found to be in good agreement with those observed in experiments. In addition, film orientations and patterns necessary to achieve large actuation strains are suggested for dome-shaped and tunnel-shaped microactuators. It is found that the resulting morphologies evolve with coherent interfaces under various loading conditions. This suggests that compatible walls provide a low-energy path during evolution, and the understanding of them leads to novel strategies of large strain actuation. © 2008 Acta Materialia Inc.
Subjects
Martensite; Pattern formation; Thin films
Other Subjects
Arsenic compounds; Lithography; Martensite; Microstructure; Phase interfaces; Strain; Thick films; Thin films; Coherent interfaces; Evolution (CO); Field variables; Film orientations; Hierarchical structuring; Large strains; Loading conditions; Low energies; Martensitic microstructure; Martensitic thin films; Novel strategies; Pattern formations; Phase field method (PFM); Trigonal symmetry; Well structure; Coarsening
Type
journal article
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