Analysis of flow-stress measurements of high-purity tungsten single crystals

Brunner, D.; Glebovsky, V.G.

doi:10.1016/s0167-577x(00)00017-3

Cited by 45 publications

(26 citation statements)

References 24 publications

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“…This finding is in agreement with atomistic studies presented in Part I. An interesting result of the calculations is that while the (101)[111] system operates at all temperatures in tension, in compression the system (110)[1 1 1] becomes dominant at temperatures below 150 K. Unfortunately, no experimental measurements of the yield stress in compression that would be of similar accuracy as the measurements in [45] are available to test these predicted features of the plastic yielding in tungsten. Table 2.…”

Section: Comparisons With Experimental Measurements Of the Temperatursupporting

confidence: 88%

“…However, since for ! " = 0 the activation enthalpy is equal to 2H k , the energy of a kink can be estimated with high precision from experimental data of the temperature dependence of the flow stress at low stresses [44,45] and/or from studies of internal friction [46]. Values of 2H k determined in this way for Mo and W are presented in Table 2.…”

Section: Activation Enthalpy For Dislocation Glide and Temperature Dementioning

confidence: 99%

“…! ) obtained for Mo and W from experiments in [44] and [45], respectively, are given in Table 2. Table 2: Energy of two isolated kinks deduced from experiments in [44] and [45], the shear modulus µ entering the expression for the line tension, temperature T k at which the thermal component of the yield stress in tension vanishes and corresponding values of ln Finally, it should be noted that several slip systems may operate concurrently when deforming a single crystal and thus the total plastic strain is…”

Section: Activation Enthalpy For Dislocation Glide and Temperature Dementioning

confidence: 99%

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Multiscale modeling of plastic deformation of molybdenum and tungsten. III. Effects of temperature and plastic strain rate

Gröger

Vítek

2008

Acta Materialia

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In this paper we develop a link between the atomic-level modeling of the glide of 1/2〈111〉 screw dislocations at 0 K and the thermally activated motion of these dislocations via nucleation of pairs of kinks. For this purpose, we introduce the concept of a hypothetical Peierls barrier, which reproduces all the aspects of the dislocation glide at 0 K resulting from the complex response to non-glide stresses and expressed in a compact form by the yield criteria advanced in Part II. To achieve this the barrier is dependent not only on the crystal symmetry and interatomic bonding but also on the applied stress tensor. Standard models are then employed to evaluate the activation enthalpy of kink-pairs formation, which is now also a function of the full applied stress tensor. The transition states theory links then this mechanism with the temperature and strain rate dependence of the yield stress.

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Section: Comparisons With Experimental Measurements Of the Temperatursupporting

confidence: 88%

Section: Activation Enthalpy For Dislocation Glide and Temperature Dementioning

confidence: 99%

Section: Activation Enthalpy For Dislocation Glide and Temperature Dementioning

confidence: 99%

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Multiscale modeling of plastic deformation of molybdenum and tungsten. III. Effects of temperature and plastic strain rate

Gröger

Vítek

2008

Acta Materialia

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“…On the other hand, for the two bcc metals, Fe and Ta, UFG microstructure leads to obviously reduced rate sensitivity. The experimentally derived activation volumes for UFG Fe and Ta are of the same order as that observed in large-grained bcc metals at very high stresses, i.e., around 10b 3 [13,29,[38][39][40].…”

Section: Mechanical Testing Resultssupporting

confidence: 54%

Effect of nanocrystalline and ultrafine grain sizes on the strain rate sensitivity and activation volume: fcc versus bcc metals

Wei

Cheng

Ramesh

et al. 2004

Materials Science and Engineering: A

808

312

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“…However, no experimental data suggest that the slip in tungsten is on ͕112͖ planes while ͕110͖ planes appear to be ubiquitous slip planes. 28,29,[136][137][138] Hence, the BOP rather than BOP 0 appears to describe correctly the glide of screw dislocations in tungsten. This again underscores the importance of screening of bond integrals that leads to accurate description of angularly dependent bonding mediated by d electrons.…”

Section: Core Structure and Effect Of Externally Applied Stressmentioning

confidence: 90%

Bond-order potential for simulations of extended defects in tungsten

et al. 2007

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We present a bond-order potential (BOP) for the bcc transition metal tungsten. The bond-order potentials are a real-space semiempirical scheme for the description of interatomic interactions based on the tight-binding approximation. In the hierarchy of atomic-scale-modeling methods the BOPs thus provide a direct bridge between electronic-structure and atomistic techniques. Two variants of the BOP were constructed and extensively tested against accurate first-principles methods in order to assess the potentials' reliability and applicability. A comparison of the BOP with a central-force potential is used to demonstrate that a correct description of directional mixed covalent and metallic bonds is crucial for a successful and fully transferable model. The potentials are applied in studies of low-index surfaces, symmetrical tilt grain boundaries, and dislocations. We present a bond-order potential ͑BOP͒ for the bcc transition metal tungsten. The bond-order potentials are a real-space semiempirical scheme for the description of interatomic interactions based on the tight-binding approximation. In the hierarchy of atomic-scale-modeling methods the BOPs thus provide a direct bridge between electronic-structure and atomistic techniques. Two variants of the BOP were constructed and extensively tested against accurate first-principles methods in order to assess the potentials' reliability and applicability. A comparison of the BOP with a central-force potential is used to demonstrate that a correct description of directional mixed covalent and metallic bonds is crucial for a successful and fully transferable model. The potentials are applied in studies of low-index surfaces, symmetrical tilt grain boundaries, and dislocations.

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Analysis of flow-stress measurements of high-purity tungsten single crystals

Cited by 45 publications

References 24 publications

Multiscale modeling of plastic deformation of molybdenum and tungsten. III. Effects of temperature and plastic strain rate

Multiscale modeling of plastic deformation of molybdenum and tungsten. III. Effects of temperature and plastic strain rate

Effect of nanocrystalline and ultrafine grain sizes on the strain rate sensitivity and activation volume: fcc versus bcc metals

Bond-order potential for simulations of extended defects in tungsten

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