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Messmer C, Dew-hughes D, Bilello JC. Effect of prior deformation on the cleavage of zinc single crystals. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/13642818308246466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Affiliation(s)
- A. Kelly
- a Department of Metallurgy , University of Cambridge
| | - W. R. Tyson
- b Department of Materials Science , University of Toronto
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Abstract
A dynamic crack tip shielding model has been developed to describe the brittle-ductile transition (BDT) of precracked crystals in constant strain-rate tests. Dislocations are emitted from a discrete number of sources at or near the crack tip. At the BDT the dislocations are emitted and move sufficiently rapidly to shield the most vulnerable parts of the crack, furthest away from the sources, such that the local stress intensity factor remains below
K
Ic
for values of the applied stress intensity factor
K
above
K
Ic
. Computer simulations of the dynamics of dislocation generation from the crack tip sources, assuming mode III loading, suggest that a sharp transition as observed in silicon is predicted only if generation starts at
K
≡
K
0
≈
K
Ic
, but then continues at
K
≡
K
N
≪
K
Ic
. Dislocation etch pit studies reported by Samuels & Roberts (
Proc. R. Soc. Lond.
A 421, 1─23 (1989)) (hereafter called I) confirm that generation begins at
K
0
≈
K
Ic
. It is suggested that
K
0
corresponds to the value of
K
at which a crack tip source is nucleated by movement of an existing dislocation in the crystal to the crack tip. The model accounts quantitatively for the strain-rate dependence of the transition temperature
T
c
reported in I, and predicts a dependence of
T
c
on dislocation density, in qualitative agreement with (unpublished) experiments. Calcluations of the strees field around the crack tip of a semicircular precrack, suggest that the ends of the half loops emitted by crack tip sources undergo multiple cross slip to follow the crack profile. The predicted dislocation configurations agree with etch pit observations reported in I.
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Riedle J, Gumbsch P, Fischmeister HF. Cleavage anisotropy in tungsten single crystals. PHYSICAL REVIEW LETTERS 1996; 76:3594-3597. [PMID: 10061007 DOI: 10.1103/physrevlett.76.3594] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Kohlhoff S, Gumbsch P, Fischmeister HF. Crack propagation in b.c.c. crystals studied with a combined finite-element and atomistic model. ACTA ACUST UNITED AC 1991. [DOI: 10.1080/01418619108213953] [Citation(s) in RCA: 286] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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The dynamics of dislocation generation at crack tips and the ductile-brittle transition. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/0036-9748(87)90294-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Effect of impurity element substitution on the failure behavior of a W-Ni-Fe alloy. ACTA ACUST UNITED AC 1983. [DOI: 10.1007/bf00805553] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Pharr G, Barnett D, Nix W. A critique of the ayres-stein method of predicting cleavage planes in metals. ACTA ACUST UNITED AC 1978. [DOI: 10.1016/0036-9748(78)90005-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Weiss K. Eine elektrochemische Methode zur Abschätzung der Oberflächenenergie von α-Ag2S. J SOLID STATE CHEM 1972. [DOI: 10.1016/0022-4596(72)90085-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ayres R, Stein D. A dislocation dynamics approach to prediction of cleavage planes in b.c.c. metals. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/0001-6160(71)90135-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Knott J. Mechanics and mechanisms of large-scale brittle fracture in structural metals. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/0025-5416(71)90058-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Smith E. Cleavage crack formation and the effect of the structure of the nucleating deformation process. ACTA ACUST UNITED AC 1968. [DOI: 10.1016/0001-6160(68)90016-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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