Influences of granular constraints and surface effects on the heterogeneity of elastic, superelastic, and plastic responses of polycrystalline shape memory alloys [electronic resource].

Published:: Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2017.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description:: pages 46-66 : digital, PDF file
Additional Creators:: Argonne National Laboratory, United States. Department of Energy. Office of Basic Energy Sciences, National Science Foundation (U.S.), and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

Deformation heterogeneities at the microstructural length-scale developed in polycrystalline shape memory alloys (SMAs) during superelastic loading are studied using both experiments and simulations. In situ X-ray diffraction, specifically the far-field high energy diffraction microscopy (ff-HEDM) technique, was used to non-destructively measure the grain-averaged statistics of position, crystal orientation, elastic strain tensor, and volume for hundreds of austenite grains in a superelastically loaded nickel-titanium (NiTi) SMA. These experimental data were also used to create a synthetic microstructure within a finite element model. The development of intragranular stresses were then simulated during tensile loading of the model using anisotropic elasticity. Driving forces for phase transformation and slip were calculated from these stresses. The grain-average responses of individual austenite crystals examined before and after multiple stress-induced transformation events showed that grains in the specimen interior carry more axial stress than the surface grains as the superelastic response "shakes down". Examination of the heterogeneity within individual grains showed that regions near grain boundaries exhibit larger stress variation compared to the grain interiors. As a result, this intragranular heterogeneity is more strongly driven by the constraints of neighboring grains than the initial stress state and orientation of the individual grains.

Report Numbers:

E 1.99:1365399

Subject(s):

Materials Science

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Note:

Published through SciTech Connect.
02/16/2017.
"132343"
Journal of the Mechanics and Physics of Solids 102 C ISSN 0022-5096 AM
Harshad M. Paranjape; Partha P. Paul; Hemant Sharma; Peter Kenesei; Jun -Sang Park; T. W. Duerig; L. Catherine Brinson; Aaron P. Stebner.

Funding Information:

AC02-06CH11357

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