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Science. 2017 Oct 6;358(6359):97-101. doi: 10.1126/science.aam8256.

Segregation-induced ordered superstructures at general grain boundaries in a nickel-bismuth alloy.

Author information

1
Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015, USA.
2
Department of Mechanical Engineering, Rose-Hulman Institute of Technology, Terre Haute, IN 47803, USA.
3
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
4
Department of NanoEngineering, Program of Materials Science and Engineering, University of California, San Diego, La Jolla, CA 92093, USA.
5
Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
6
Department of NanoEngineering, Program of Materials Science and Engineering, University of California, San Diego, La Jolla, CA 92093, USA. mph2@lehigh.edu jluo@alum.mit.edu.
7
Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015, USA. mph2@lehigh.edu jluo@alum.mit.edu.

Abstract

The properties of materials change, sometimes catastrophically, as alloying elements and impurities accumulate preferentially at grain boundaries. Studies of bicrystals show that regular atomic patterns often arise as a result of this solute segregation at high-symmetry boundaries, but it is not known whether superstructures exist at general grain boundaries in polycrystals. In bismuth-doped polycrystalline nickel, we found that ordered, segregation-induced grain boundary superstructures occur at randomly selected general grain boundaries, and that these reconstructions are driven by the orientation of the terminating grain surfaces rather than by lattice matching between grains. This discovery shows that adsorbate-induced superstructures are not limited to special grain boundaries but may exist at a variety of general grain boundaries, and hence they can affect the performance of polycrystalline engineering alloys.

PMID:
28983049
DOI:
10.1126/science.aam8256

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