NiAl-based eutectic alloys, consisting of an ordered bcc matrix (B2) and disordered bcc fibers (A2), have been a subject of intensive efforts aimed at tailoring the properties of many of the currently used nickel-based superalloys. A thermodynamic phase field model was developed on a thermodynamic foundation and fully integrated with a thermo-kinetic database of the Ni-Al-Cr ternary system to elucidate the resulting peculiar eutectic microstructure. Invoking a variation of the liquid/solid interfacial thickness with temperature, we simulated the characteristic sunflower-like eutectic microstructures in the NiAl-Cr composites, consistent with experimental observations. The mechanism that governs the formation of the peculiar eutectic morphology was envisioned from the modeled evolutions associated with six sequential steps. Our calculations show that the conditional spinodal decomposition occurring in sequence could further trim and revise the microstructure of the eutectics by generating fine-domain structures, thereby providing an additional method to explore the novel NiAl-based eutectic composites with tunable properties at elevated temperatures.

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Single crystalline tungsten nanowires were prepared from directionally solidified NiAl-W alloys by a chemical release from the resulting binary phase material. Electron back scatter diffraction (EBSD) proves that they are single crystals having identical crystallographic orientation. Mechanical investigations such as bending tests, lateral force measurements, and mechanical resonance measurements were performed on 100–300 nm diameter wires. The wires could be either directly employed using micro tweezers, as a singly clamped nanowire or in a doubly clamped nanobridge. The mechanical tests exhibit a surprisingly high flexibility for such a brittle material resulting from the small dimensions. Force displacement measurements on singly clamped W nanowires by an AFM measurement allowed the determination of a Young's modulus of 332 GPa very close to the bulk value of 355 GPa. Doubly clamped W nanowires were employed as resonant oscillating nanowires in a magnetomotively driven resonator running at 117 kHz. The Young's modulus determined from this setup was found to be higher 450 GPa which is likely to be an artefact resulting from the shift of the resonance frequency by an additional mass loading.

Gold nanobelts were synthesized by directional solidification of the Fe-Au eutectoid followed by selective phase dissolution. Cleaning from organic molecules was performed in alkaline solution by PbO(2) deposition/dissolution to avoid surface reconstruction. The electrochemical behaviour of the Au nanobelts was determined by structure-sensitive electrochemical reactions, and the findings confirm the results obtained by selected area electron diffraction (SAED). The underpotential deposition (UPD) of lead under alkaline conditions and cyclic voltammograms (CVs) in sulphuric acid revealed an unusual large amount of (110) domains (>65%). Finally, after cleaning the Au nanobelts showed a higher and stable electrocatalytic behaviour toward methanol oxidation in alkaline media. The possible mechanism and the potential applications of the Au nanobelts are discussed.

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For the first time single crystalline gold nanobelt arrays with identical crystallographic orientation were obtained. A combined method consisting of directional solid-state transformation of a Fe-Au eutectoid and a well controlled electrochemical treatment enables production of arrays of nanobelts with a desired length. They have an average thickness of 25 nm and width of 200-250 nm, respectively. The obtained gold nanobelt arrays were characterized by electron backscattered diffraction (EBSD), X-ray diffraction, and XPS. The underlying mechanisms and the potential of this method for the production of nanosensors are discussed.

The effects of the solidification parameters, such as growth rate and temperature gradient, on the distance and diameter of Re nanowires have been examined. Both the spacing and diameter increase with decreasing growth rate and temperature gradient, respectively. The ratio of fiber spacing to diameter is 9.1. In addition, it was demonstrated that the temperature gradient influences interface undercooling in the same way as the growth rate and may be used as an additional parameter to control fiber spacing and diameter.