Combinatorial Exploration and Mapping of Phase Transformation in a Ni-Ti-Co Thin Film Library

Al Hasan, N.M. and Hou, H. and Gao, T. and Counsell, J. and Sarker, S. and Thienhaus, S. and Walton, E. and Decker, P. and Mehta, A. and Ludwig, Al. and Takeuchi, I.

Volume: 22 Pages: 641-648
DOI: 10.1021/acscombsci.0c00097
Published: 2020

Combinatorial synthesis and high-throughput characterization of a Ni-Ti-Co thin film materials library are reported for exploration of reversible martensitic transformation. The library was prepared by magnetron co-sputtering, annealed in vacuum at 500 °C without atmospheric exposure, and evaluated for shape memory behavior as an indicator of transformation. Composition, structure, and transformation behavior of the 177 pads in the library were characterized using high-throughput wavelength dispersive spectroscopy (WDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and four-point probe temperature-dependent resistance (R(T)) measurements. A new, expanded composition space having phase transformation with low thermal hysteresis and Co > 10 at. % is found. Unsupervised machine learning methods of hierarchical clustering were employed to streamline data processing of the large XRD and XPS data sets. Through cluster analysis of XRD data, we identified and mapped the constituent structural phases. Composition-structure-property maps for the ternary system are made to correlate the functional properties to the local microstructure and composition of the Ni-Ti-Co thin film library. © 2020 American Chemical Society. All rights reserved.

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