Toughening of Li2O‐2SiO2 glass‐ceramics induced by intriguing deformation behavior of lithium disilicate nanocrystal

We report a toughening mechanism of Li2O‐2SiO2 glass‐ceramics induced by intriguing anisotropic deformation behavior of lithium disilicate nanocrystal under tensile loadings using molecular dynamics simulations. The nanocrystal undergoes clear brittle cleavage when loaded in the [010] direction, whi...

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Bibliographic Details
Published in:Journal of the American Ceramic Society Vol. 103; no. 2; pp. 965 - 972
Main Authors: Deng, Binghui, Luo, Jian, Harris, Jason T., Smith, Charlene M., McKenzie, Matthew E.
Format: Journal Article
Language:English
Published: Columbus Wiley Subscription Services, Inc 01.02.2020
Subjects:
anisotropy
Breakage
Ceramics
Deformation mechanisms
first‐order transition
fracture toughness
Glass
Lithium
lithium disilicate
Lithium oxides
Loads (forces)
Molecular dynamics
Nanocrystals
Toughening
ISSN:0002-7820, 1551-2916
Online Access:Get full text
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Summary:We report a toughening mechanism of Li2O‐2SiO2 glass‐ceramics induced by intriguing anisotropic deformation behavior of lithium disilicate nanocrystal under tensile loadings using molecular dynamics simulations. The nanocrystal undergoes clear brittle cleavage when loaded in the [010] direction, while exhibiting a first‐order deformation‐induced transition when loaded in the [100] direction. The transition is exclusively facilitated by local Li–O bond breaking, which spreads to the whole sample under continuous loading. This hierarchical deformation mechanism (exclusive Li–O bond breakage prior to any Si–O bond breakage) enables lithium disilicate nanocrystal bearing large amounts of deformation without breaking. We further demonstrate that the toughness of Li2O‐2SiO2 glass‐ceramics can be significantly enhanced by deliberate designs of nanocrystal distributions in glass. The direct observation of this intriguing deformation behavior might inspire new ideas to design tougher lithium disilicate glass‐ceramics. The deformation morphology of a lithium disilicate glass‐ceramics sample inserted with randomly oridented LS2 crystals that exhibits intriguing anisotropic stress‐strain response.
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ISSN:0002-7820
1551-2916
DOI:10.1111/jace.16794