Fracture studies of tungsten single crystals

Riedle, Joachim; Gumbsch, Peter; Fischmeister, H. F.; Glebovsky, V.G.; Семенов, В. Н.

doi:10.1016/0167-577x(94)90036-1

Cited by 27 publications

(11 citation statements)

References 9 publications

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“…In this case, the measured K Ic at 77K is (4.6±0.3) MPa m 1/2 , double that of the single crystal material. This is probably due to the varied orientation of the small grains which will hinder the propagation of cracks on the lowest-energy {001} fracture planes [17]. In polycrystalline tungsten, as in single-crystals, the fracture toughness increases gradually with increasing temperature up to T BDT for all the strain rates investigated.…”

Section: Resultsmentioning

confidence: 92%

Strain-rate dependence of the brittle-to-ductile transition temperature in tungsten

Giannattasio¹,

Roberts²

2007

Philosophical Magazine

163

110

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rate dependence of the brittle-to-ductile transition temperature in tungsten. Philosophical Magazine, Taylor & Francis, 2008, 87 (17) AbstractWe have investigated the strain rate dependence of the brittle-to-ductile transition (BDT) temperature in pre-cracked tungsten single-crystals and polycrystals. There is an unambiguousArrhenius relationship over four decades of strain rate, giving an activation energy for the process controlling the BDT of 1.05 eV. This is equal to the activation energy for double-kink formation on screw dislocations, suggesting that their motion controls the brittle-ductile transition.

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Section: Resultsmentioning

confidence: 92%

Strain-rate dependence of the brittle-to-ductile transition temperature in tungsten

Giannattasio¹,

Roberts²

2007

Philosophical Magazine

163

110

View full text Add to dashboard Cite

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“…The substructures of the molybdenum single crystals vary seriously depending on the growth rate (Glebovsky et al, 1988;Glebovsky & Semenov, 1994Glover et al, 1970, Liu & Zee, 1996. At high growth rates the substructure is characterized by the high dislocation density and the more stressed state.…”

Section: The Substructure Of the Molybdenum Single Crystalsmentioning

confidence: 99%

“…This necessitates both studying purification processes and developing advanced methods of growing single crystals metals using modern electron beam guns (M. Cole et al, 1968;Glebovsky et al, 1986). The main purpose in this field is to study the real structure of single crystals as a function of the technological parameters of the EBFZM method (Langer, 1980;Riedle et al, 1994Riedle et al, , 1996. For effective melting and growing, the original EB guns have been elaborated on because the EB guns is the most important element of the EBFZM set-ups (Glebovsky et al, 1986;Shah, 1980).…”

Section: Features Of the Single Crystals Growthmentioning

confidence: 99%

“…The as-grown single crystals are 11-22 mm in dia and 100 mm in length. The structural studies involve the X-ray diffraction microscopy methods, namely, angular scanning topography and rocking curves (Aristov et al, 1974;Bozhko et al, 2008;Brunner & Glebovsky, 2000a, 2000bErmolov et al, 1999Ermolov et al, , 2002Riedle et al, 1994Riedle et al, , 1996.…”

Section: Experiments On Recrystallization Of the Tungsten Single Crysmentioning

confidence: 99%

“…Modern methods of preparing the tungsten single crystals can produce the specimens having the dislocation density of about 10 5 cm -2 . A chemical composition, a growth rate, a number of passes by the liquid zone, geometry of the crystals and some other parameters of the growth in varying degrees affect the substructure, but in any case, the substructure of the crystals of molybdenum and tungsten grown from the melt is far imperfect (Glebovsky et al, 1988;Glebovsky & Semenov, 1993-1994 However, the single crystals, free of the specific substructure, can be grown by the secondary recrystallization process, which consists of the plastic deformation procedure and the high-temperature annealing procedure. The plastic deformation procedure of monocrystalline specimens can be produced by rolling in the vacuum rolling machines.…”

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confidence: 99%

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Crystal Growth: Substructure and Recrystallization

Glebovsky¹

2012

Recrystallization

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A non‐planar crack analysis using continuously distributed sinusoidal edge dislocations and linear elasticity

Anongba

1996

Physica Status Solidi (b)

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Non-planar cracks; propagating along crystallographic directions in the cleavage fracture of brittle materials and fluctuating about a mean plane, are represented in a simple model by a distribution of sinusoidal edge dislocations in a linear elastic medium; the dislocations are perpendicular to the crack propagation direction. The opening mode I loading is assumed. It is shown that, at the front of the sinusoidal crack and out of the mean fracture plane, the stresses are bounded and the derivative G of the energy decrease of the system with respect to crack area is zero. Only the positions of the crack front located on the mean fracture plane are associated with a nonzero value of G always lower than the well-known crack opening force Go = K ? ( l ~ v 2 ) / E per unit edge length of the planar crack ( K I is the stress intensity factor of mode I loading and E is Young's modulus). It is concluded that the sinusoidal crack cannot start propagating from positions on the crack front that are out of the mean fracture plane; instead, crack propagation could begin very near to the intersections of the crack front with the mean fracture plane if certain assumptions about the anisotropy of the surface energy are made.Des fissures non planes, se propageant suivarit des directions cristallographiques pendant le clivage des mat6riaux fragiles et fluctuant autour d'un plan moyen, sont reprksentkes par une distribution de dislocations sinusdidales coins en milieu klastique linkaire; Ies dislocations sont perpendiculaires k la direction dc propagation de la fissure. Le mode I de fracture est considkrC. On montre que, k l'extrkmit6 de la fissure sinusoidale et hors du plan de fracture moyen, les contraintes sont bornkes et la dkrivke G de la diminution de I'Cnergie du systkme par unit6 de surface de fracture est nulle; seuls Ies points du front de fissiire, situCs sur le plan moyen de rupture, sont assoc non nulle de G toujours plus faible que la force de propagation de la fissure plane Go = Kt(1 -v 2 ) / E par unite de longueur du front de fissure (KI est le facteur d'intensitk de contrainte en mode I et E est le module de Young). I1 est conch que la fissure sinusoi'dale ne pcut commencer i se propager B partir de positions du front de fissure situkes hors du plan de fracture moyen; sa propagation peut cependant itre initike k partir des positions situkes sur le plan de fracture rnoyen si des hypothhses adkquates siir l'anisotropic de 1'Cnergie dc surface sont formulkes. ') Heisenbergstr. 1; D-70569 Stuttgart, Federal Republic of Germany. ') Present address: Dkpartement, de Physique, FAST, Universitk Nationale de C6te d'Ivoire, 22 BP 582 Abidjan, Ivory Coast,.

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Fracture studies of tungsten single crystals

Cited by 27 publications

References 9 publications

Strain-rate dependence of the brittle-to-ductile transition temperature in tungsten

Strain-rate dependence of the brittle-to-ductile transition temperature in tungsten

Crystal Growth: Substructure and Recrystallization

A non‐planar crack analysis using continuously distributed sinusoidal edge dislocations and linear elasticity

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