In ACS combinatorial science
Combinatorial synthesis and high-throughput characterization of a Ni-Ti-Co thin film materials library is reported for exploration of reversible martensitic transformation. The library was prepared by magnetron co-sputtering and annealed in vacuum at 500 °C and evaluated for shape memory behavior. 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 datasets. 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.
Al Hasan Naila Mahmood, Hou Huilong, Gao Tieren, Counsell Jonathan D P, Sarker Suchismita, Thienhaus Sigurd, Walton Edward, Decker Peer, Mehta Apurva, Ludwig Alfred, Takeuchi Ichiro