High‐voltage electron microscopy analyses for crack‐tip dislocations and their shielding effect on fracture toughness in MgO and Si crystals.
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| Title: | High‐voltage electron microscopy analyses for crack‐tip dislocations and their shielding effect on fracture toughness in MgO and Si crystals. |
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| Authors: | Higashida, Kenji1 (AUTHOR) higashida.kenji.249@m.kyushu-u.ac.jp, Sadamatsu, Sunao2 (AUTHOR), Tanaka, Masaki1 (AUTHOR) |
| Source: | Journal of the American Ceramic Society. Jun2025, Vol. 108 Issue 6, p1-12. 12p. |
| Subjects: | Dislocation loops, Dislocation structure, Ionic crystals, Material plasticity, Fracture toughness |
| Abstract: | In this study, characteristics of dislocation structures around a crack‐tip in both crystals of MgO and Si were investigated using high‐voltage electron microscopy (HVEM). The interaction between a crack and dislocations was analyzed to discuss the effect of crack‐tip plasticity on fracture toughness. The present paper first demonstrates a dislocation configuration around a crack‐tip in a MgO thin crystal, where the plastic zone called 45°‐shear type is dominant under the plane stress condition. Then, the slip systems necessary for brittle‐to‐ductile transition in ionic crystals with the rock‐salt structure are discussed based on the temperature dependence of stress‐strain relationships and the aspect of crack front observed in NaCl crystals. Second, crack‐tip dislocations near the surface of bulk Si crystals are exhibited based on the 3D analyses using HVEM tomography. We focus on a newfound plastic zone being perpendicular to the crack plane, which is different from either 45°‐shear type or the hinge type generally well‐known. The dislocation loops observed in this plastic zone fundamentally have a crack‐tip shielding effect to increase fracture toughness. Still, in addition, they contribute to activating crack‐tip dislocations by their localized antishielding field. These analyses reveal a fundamental toughening mechanism for crystalline materials. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of the American Ceramic Society is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Header | DbId: egs DbLabel: Engineering Source An: 184273604 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: High‐voltage electron microscopy analyses for crack‐tip dislocations and their shielding effect on fracture toughness in MgO and Si crystals. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Higashida%2C+Kenji%22">Higashida, Kenji</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> higashida.kenji.249@m.kyushu-u.ac.jp</i><br /><searchLink fieldCode="AR" term="%22Sadamatsu%2C+Sunao%22">Sadamatsu, Sunao</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Tanaka%2C+Masaki%22">Tanaka, Masaki</searchLink><relatesTo>1</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+the+American+Ceramic+Society%22">Journal of the American Ceramic Society</searchLink>. Jun2025, Vol. 108 Issue 6, p1-12. 12p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Dislocation+loops%22">Dislocation loops</searchLink><br /><searchLink fieldCode="DE" term="%22Dislocation+structure%22">Dislocation structure</searchLink><br /><searchLink fieldCode="DE" term="%22Ionic+crystals%22">Ionic crystals</searchLink><br /><searchLink fieldCode="DE" term="%22Material+plasticity%22">Material plasticity</searchLink><br /><searchLink fieldCode="DE" term="%22Fracture+toughness%22">Fracture toughness</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: In this study, characteristics of dislocation structures around a crack‐tip in both crystals of MgO and Si were investigated using high‐voltage electron microscopy (HVEM). The interaction between a crack and dislocations was analyzed to discuss the effect of crack‐tip plasticity on fracture toughness. The present paper first demonstrates a dislocation configuration around a crack‐tip in a MgO thin crystal, where the plastic zone called 45°‐shear type is dominant under the plane stress condition. Then, the slip systems necessary for brittle‐to‐ductile transition in ionic crystals with the rock‐salt structure are discussed based on the temperature dependence of stress‐strain relationships and the aspect of crack front observed in NaCl crystals. Second, crack‐tip dislocations near the surface of bulk Si crystals are exhibited based on the 3D analyses using HVEM tomography. We focus on a newfound plastic zone being perpendicular to the crack plane, which is different from either 45°‐shear type or the hinge type generally well‐known. The dislocation loops observed in this plastic zone fundamentally have a crack‐tip shielding effect to increase fracture toughness. Still, in addition, they contribute to activating crack‐tip dislocations by their localized antishielding field. These analyses reveal a fundamental toughening mechanism for crystalline materials. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of the American Ceramic Society is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1111/jace.20378 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 12 StartPage: 1 Subjects: – SubjectFull: Dislocation loops Type: general – SubjectFull: Dislocation structure Type: general – SubjectFull: Ionic crystals Type: general – SubjectFull: Material plasticity Type: general – SubjectFull: Fracture toughness Type: general Titles: – TitleFull: High‐voltage electron microscopy analyses for crack‐tip dislocations and their shielding effect on fracture toughness in MgO and Si crystals. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Higashida, Kenji – PersonEntity: Name: NameFull: Sadamatsu, Sunao – PersonEntity: Name: NameFull: Tanaka, Masaki IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 06 Text: Jun2025 Type: published Y: 2025 Identifiers: – Type: issn-print Value: 00027820 Numbering: – Type: volume Value: 108 – Type: issue Value: 6 Titles: – TitleFull: Journal of the American Ceramic Society Type: main |
| ResultId | 1 |
