A model of dislocation multiplication at a crack tip: influence on the brittle to ductile transition

Michot, G.; Oliveira, M.A. Loyola de; Champier, G.

doi:10.1016/s0921-5093(99)00473-6

Cited by 24 publications

(10 citation statements)

References 31 publications

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“…Concerning the latter property, more accurate experiments can be designed by testing pre-cracked poly or single crystals. These experiments are close to those performed on silicon single crystals (Michot et al 1999), in which the loading rateσ was replaced by a variable more representative of fracture problems,K.…”

Section: Discussionsupporting

confidence: 69%

The Brazilian test: a tool for measuring the toughness of a material and its brittle to ductile transition

Proveti¹,

Michot

2006

Int J Fract

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Due to their brittleness, assembling of ceramics pieces is generally achieved through brazing but thermal stresses during cooling frequently induce cracking of the material used for brazing. In order to check if such damage is avoidable, it is necessary to characterize the brittle to ductile transition (BDT) of the material. Simple compression is not suited for crack studies, because of mixed loading (mode II + compressive mode I cracking). Another type of test, the cylinder splitting test, known as the Brazilian test, can be carried out by applying compressive forces on two opposite generatrix of a cylinder: this causes a uniform tensile stress on the plane containing the axis of the cylinder and the generatrix, leading to mode I cracking. The advantage of this test is to avoid expensive and random machining of brittle samples. This study shows that the Brazilian test is well adapted for the measurement of toughness and the characterization of the BDT of materials whose room temperature behaviour is brittle (silicides, intermetallics etc.).

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Section: Discussionsupporting

confidence: 69%

The Brazilian test: a tool for measuring the toughness of a material and its brittle to ductile transition

Proveti¹,

Michot

2006

Int J Fract

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“…Such defects can be preexisting ledges (8) , but may be also caused by the intersection of dislocations with the crack front (2), (7), (9) . In-situ X-Ray topography experiments in Si have shown that a single dislocation intersecting the crack front can stimulate the emission of other dislocations in an avalanche-type multiplication process (7), (9), (10) . Such dislocation sources created at the crack front by intersecting dislocations are believed to play an important role in the fracture behavior of all brittle materials.…”

Section: Introductionmentioning

confidence: 99%

Atomistic Simulations of Dislocation - Crack Interaction

Bitzek

Gumbsch

2008

JMMP

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The interaction of dislocations with a static mode I crack is studied by large scale molecular dynamics simulations. The model consists of a blunted [001](110) crack in nickel, to which after relaxation at K < K Ic the displacement field of a dislocation is added. The response of the system is monitored during its evolution in the microcanonical ensemble. The simulations allowed to identify different characteristic processes during the interaction of the impinging dislocation with the crack. In particular, stimulated dislocation emission and cross slip processes are observed to be important for the development of a plastic zone.

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“…The elastic strain around the dislocation is also expected to be high. (5) and (6) derives the elastic strain there to be approximately 0.02. Such high elastic strain around the dislocation core will be measured by using the GPA.…”

Section: Y Xmentioning

confidence: 99%

“…Since the fracture toughness of silicon single crystals abruptly increases at the BDT temperature, they have been used as model crystals to understand the mechanism behind the BDT. It was found that the increase in the fracture toughness is due to a shielding effect of dislocations emitted from a crack tip [3,5,6,7].…”

Section: Introductionmentioning

confidence: 99%

Strain Field Around Lomer Sessile Dislocations in Silicon Measured using Geometric Phase Analysis

Adhika

Tanaka

Yamamoto

et al. 2015

Trans. Mat. Res. Soc. Japan

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Strain fields around dislocation pairs were measured using geometrical phase analysis of high-resolution TEM images. Single crystalline (011) silicon wafers were employed. The wafers were deformed using three-point bending at 1123K in order to introduce dislocations. The observed dislocations were found to be Lomer sessile dislocations. The strain fields around the dislocations experimentally measured were in good agreement with those calculated from the elastic theory. Experimental results showed that the strain field of two dislocations can be regarded as a single dislocation when their distance is less than 6b.

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A model of dislocation multiplication at a crack tip: influence on the brittle to ductile transition

Cited by 24 publications

References 31 publications

The Brazilian test: a tool for measuring the toughness of a material and its brittle to ductile transition

The Brazilian test: a tool for measuring the toughness of a material and its brittle to ductile transition

Atomistic Simulations of Dislocation - Crack Interaction

Strain Field Around Lomer Sessile Dislocations in Silicon Measured using Geometric Phase Analysis

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