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arXiv · 1810.06141

Three-dimensional in situ characterization of phase transformation induced austenite grain refinement in nickel-titanium

Ashley N. Bucsek·Lee Casalena·Darren C. Pagan·Partha P. Paul·Yuriy Chumlyakov·Michael J. Mills·Aaron P. Stebner
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Abstract

Near-field and far-field high-energy diffraction microscopy and microcomputed tomography X-ray techniques were used to study a bulk single crystal nickel-titanium shape memory alloy sample subjected to thermal cycling under a constant applied load. Three-dimensional in situ reconstructions of the austenite microstructure are presented, including the structure and distribution of emergent grain boundaries. After one cycle, the subgrain structure is significantly refined, and heterogeneous {\Sigma}3 and {\Sigma}9 grain boundaries emerge. The low volume and uneven dispersion of the emergent {\Sigma} boundaries across the volume show why previous transmission electron microscopy investigations of {\Sigma} grain boundary formation were inconsistent.

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Ashley N. Bucsek, Lee Casalena, Darren C. Pagan, Partha P. Paul, Yuriy Chumlyakov, Michael J. Mills, Aaron P. Stebner. 2018-10-15. Three-dimensional in situ characterization of phase transformation induced austenite grain refinement in nickel-titanium. https://arxiv.org/abs/1810.06141

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