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3-D structures of crack-tip dislocations and their shielding effect revealed by electron tomography.

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Title: 3-D structures of crack-tip dislocations and their shielding effect revealed by electron tomography.
Authors: Tanaka, Masaki1 masaki@zaiko.kyushu-u.ac.jp, Honda, Masaki1, Sadamatsu, Sunao1, Higashida, Kenji1
Source: Journal of Electron Microscopy. Aug2010 Supplement 1, Vol. 59 Issue S1, pS55-S60. 1p. 3 Black and White Photographs, 3 Diagrams.
Subjects: Dislocations in crystals, Scanning electron microscopes, Tomography, Scanning electron microscopy, Oscillations, Properties of matter
Abstract: Three-dimensional structures of crack-tip dislocations in silicon crystals have been examined by combining scanning transmission electron microscopy and computed tomography. Cracks were introduced by a Vickers hardness tester at room temperature, and the sample was heated at 823 K for 1 h in order to introduce dislocations around the crack tips. Dislocation segments cut out from loops were observed around the crack tip, the three-dimensional structure of which was characterized by using by electron tomography. Their Burgers vectors including the sings were also determined by oscillating contrasts along dislocations. In order to investigate the effect of the dislocations on fracture behaviours, local stress intensity factor due to one dislocation was calculated, which indicates the dislocations observed were shielding type to increase fracture toughness. [ABSTRACT FROM PUBLISHER]
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Database: Engineering Source
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Abstract:Three-dimensional structures of crack-tip dislocations in silicon crystals have been examined by combining scanning transmission electron microscopy and computed tomography. Cracks were introduced by a Vickers hardness tester at room temperature, and the sample was heated at 823 K for 1 h in order to introduce dislocations around the crack tips. Dislocation segments cut out from loops were observed around the crack tip, the three-dimensional structure of which was characterized by using by electron tomography. Their Burgers vectors including the sings were also determined by oscillating contrasts along dislocations. In order to investigate the effect of the dislocations on fracture behaviours, local stress intensity factor due to one dislocation was calculated, which indicates the dislocations observed were shielding type to increase fracture toughness. [ABSTRACT FROM PUBLISHER]
ISSN:00220744
DOI:10.1093/jmicro/dfq031