Softening non-metallic crystals by inhomogeneous elasticity
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Howie, P., Thompson, R., Korte-Kerzel, S., & Clegg, W. (2017). Softening non-metallic crystals by inhomogeneous elasticity. Scientific Reports, 7 (11602)https://doi.org/10.1038/s41598-017-09453-1
High temperature structural materials must be resistant to cracking and oxidation. However, most oxidation resistant materials are brittle and a significant reduction in their yield stress is required if they are to be resistant to cracking. It is shown, using density functional theory, that if a crystal's unit cell elastically deforms in an inhomogeneous manner, the yield stress is greatly reduced, consistent with observations in layered compounds, such as Ti₃SiC₂, Nb₂Co₇, W₂B₅, Ta₂C and Ta₄C₃. The mechanism by which elastic inhomogeneity reduces the yield stress is explained and the effect demonstrated in a complex metallic alloy, even though the electronegativity differences within the unit cell are less than in the layered compounds. Substantial changes appear possible, suggesting this is a first step in developing a simple way of controlling plastic flow in non-metallic crystals, enabling materials with a greater oxidation resistance and hence a higher temperature capability to be used.
ceramics, materials science, structural materials
The work was supported by the EPSRC/Rolls-Royce Strategic Partnership (EP/M005607/1).
Engineering and Physical Sciences Research Council (EP/M005607/1)
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External DOI: https://doi.org/10.1038/s41598-017-09453-1
This record's URL: https://www.repository.cam.ac.uk/handle/1810/265764
Attribution 4.0 International
Licence URL: http://creativecommons.org/licenses/by/4.0/