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Issue 29, 2016
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The formation mechanism of eutectic microstructures in NiAl–Cr composites

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Abstract

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.

Graphical abstract: The formation mechanism of eutectic microstructures in NiAl–Cr composites

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Publication details

The article was received on 22 Mar 2016, accepted on 17 Jun 2016 and first published on 24 Jun 2016


Article type: Paper
DOI: 10.1039/C6CP01921H
Citation: Phys. Chem. Chem. Phys., 2016,18, 19773-19786
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    The formation mechanism of eutectic microstructures in NiAl–Cr composites

    B. Tang, D. A. Cogswell, G. Xu, S. Milenkovic and Y. Cui, Phys. Chem. Chem. Phys., 2016, 18, 19773
    DOI: 10.1039/C6CP01921H

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