Non-schmid yield behavior in single crystals

Qin, Qing; Bassani, J.L.

doi:10.1016/0022-5096(92)90005-m

Cited by 145 publications

(86 citation statements)

References 11 publications

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“…Qin and Bassani [30,31] have proposed a framework for non-Schmid behavior and demonstrated how important features of non-planar dislocation cores in L1 2 intermetallic compounds, such as Ni 3 Al [17,60], can be introduced into a rigorous finite-strain theory. This theory captured the observed orientation dependence and tension-compression asymmetry of the yield stress in the regime of the anomalous increase of the flow stress with temperature.…”

Section: Continuum Modeling Of Plastic Flow In Single Crystals Of Molmentioning

confidence: 99%

“…Following the suggestion of Qin and Bassani [30,31], the effects of non-glide stresses may enter the flow rules for slip at the single crystal level such that the effective yield stress, τ * α -which accounts for the effects of non-glide stresses for slip system α-is a linear combination of the Schmid stress and other non-glide components of stress tensor:…”

Section: Continuum Modeling Of Plastic Flow In Single Crystals Of Molmentioning

confidence: 99%

“…An understanding of the stress-state dependence exists in the case of fcc metals [1][2][3]28,29] and some close-packed compounds [4,17,30,31], but essential information is usually lacking in models and simulations for non-close-packed materials. This information is the exact tensorial nature of the stress-state dependence of plastic flow that originates at the level of individual dislocations, which then projects into flow relations for realistic simulation of the plastic response of single crystals, polycrystals and, ultimately, components made from such materials.…”

Section: Introductionmentioning

confidence: 99%

“…Using a continuum framework for the effects of non-glide stresses [30,31] that was employed earlier in the case of Ni 3 Al [4,17], we construct the yield criterion that can accurately reproduce the stress-state dependence found in the atomistic simulations for molybdenum. This criterion, which captures the slip characteristics arising from the atomic structure and properties of dislocation cores, is then employed in a Taylor-type calculation for uniaxial stressing of a random polycrystal of bcc grains with 12 {1 1 0} 1 1 1 slip systems.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Influence of non-glide stresses on plastic flow: from atomistic to continuum modeling

Vítek

Mrovec

Bassani

2004

Materials Science and Engineering: A

121

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The Schmid law, which is accurate for face-centered-cubic (fcc) metals, assumes that only the shear stress acting in the slip plane in the slip direction controls the plastic deformation. Hence, it is implicitly assumed that the critical resolved shear stress (CRSS) for the slip is not affected by any other components of the applied stress tensor. This rule is almost ubiquitously utilized in large-scale continuum computations of plastically deforming single and polycrystals. On the other hand, in materials with more complex structures and for some orientations of the dislocation line the cores can spread onto several non-parallel planes. The most widely-known example is the screw dislocation in bcc metals, though this phenomenon is quite universal in structures that are not close packed. Signatures of such core configurations commonly include unexpected deformation modes and slip geometries, strong and unusual dependence of flow stresses on temperature and strain rate, a high Peierls stress, and, in general, a breakdown of the Schmid law. In this paper, we first summarize results of atomistic computer simulations of the response of 1/2 1 1 1 screw dislocations to the applied shear stresses. The calculations have been made using central-force many-body potentials and tight-binding based bond-order potentials for molybdenum. While the core structure found is not the same for the two descriptions of atomic interactions, both lead to a very similar orientation dependence of the critical resolved shear stress for the dislocation motion which takes place along the most highly stressed {1 1 0} plane. This dependence reveals the break down of the Schmid law invoked by the effect of shear stresses acting in another {1 1 0} plane, which are called non-glide stresses. These results are then transferred to macroscopic level by formulating single crystal yield criteria that include the effects of non-glide components of the stress tensor. These criteria form a basis for multislip yield criteria and flow relations for continuum analyses. Using this approach we demonstrate that the effects of non-glide stresses that have their origin at the level of individual dislocations also have significant effect on polycrystalline response, including a significant tension-compression asymmetry.

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Section: Continuum Modeling Of Plastic Flow In Single Crystals Of Molmentioning

confidence: 99%

Section: Continuum Modeling Of Plastic Flow In Single Crystals Of Molmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of non-glide stresses on plastic flow: from atomistic to continuum modeling

Vítek

Mrovec

Bassani

2004

Materials Science and Engineering: A

121

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“…Schmid's law, which is used to determine the active slip planes for a specific stress state [16] is known to break down for bcc metals. This particularity with a big impact on the plastic flow is referred to as non-Schmid behavior, and it implies that the critical resolved shear stress defining the onset of dislocation glide on a given slip plane varies with the sign of the applied stress and the orientation of the loading axis with respect to the lattice [17,18].…”

Section: Introductionmentioning

confidence: 99%

Linking atomistic, kinetic Monte Carlo and crystal plasticity simulations of single‐crystal tungsten strength

et al. 2015

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Understanding and improving the mechanical properties of tungsten is a critical task for the materials fusion energy program. The plastic behavior in body‐centered cubic (bcc) metals like tungsten is governed primarily by screw dislocations on the atomic scale and by ensembles and interactions of dislocations at larger scales. Modeling this behavior requires the application of methods capable of resolving each relevant scale. At the small scale, atomistic methods are used to study single dislocation properties, while at the coarse‐scale, continuum models are used to cover the interactions between dislocations. In this work we present a multiscale model that comprises atomistic, kinetic Monte Carlo (kMC) and continuum‐level crystal plasticity (CP) calculations. The function relating dislocation velocity to applied stress and temperature is obtained from the kMC model and it is used as the main source of constitutive information into a dislocation‐based CP framework. The complete model is used to perform material point simulations of single‐crystal tungsten strength. We explore the entire crystallographic orientation space of the standard triangle. Non‐Schmid effects are inlcuded in the model by considering the twinning‐antitwinning (T/AT) asymmetry in the kMC calculations. We consider the importance of 〈111〉{110} and 〈111〉{112} slip systems in the homologous temperature range from 0.08Tm to 0.33Tm, where Tm =3680 K is the melting point in tungsten. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Self-organized dislocation structures (SODS) in fatigued metals

Glazov

Llanes

Laird

1995

Phys. Stat. Sol. (a)

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An attempt to introduce a thermodynamic classification of dislocation structures produced by cyclic deformation is made. A fundamental division is proposed for all types of dislocation structures into two classes: 1. those in equilibrium and 2. strongly non-equilibrium self-organized dislocation structures ("SODS"). It is shown that the concept of low energy dislocation structures ("LEDS") introduced by Kuhlmann-Wilsdorf can be applied to dislocation structures of the first type, while the concept of SODS is useful in situations connected with the onset of fatigue instabilities (e.g., the formation of the ladder structure of persistent slip bands and dislocation rearrangements accompanying strain bursts during cyclic deformation, e.g., ramp loading). It is stressed that the issue of dislocation patterning in fatigued metals should be considered a part of the general problem of nonlinear dynamical systems functioning in far-from-equilibrium conditions. In this sense the classification proposed has common features between "physico-chemical" behavior of dipolar and multipolar dislocation populations in fatigued metallic alloys, on the one hand, and such essentially dipolar systems as ferrofluids, magnetic bubble materials, and phospholipid monolayer domains, on the other hand.

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Non-schmid yield behavior in single crystals

Cited by 145 publications

References 11 publications

Influence of non-glide stresses on plastic flow: from atomistic to continuum modeling

Influence of non-glide stresses on plastic flow: from atomistic to continuum modeling

Linking atomistic, kinetic Monte Carlo and crystal plasticity simulations of single‐crystal tungsten strength

Self-organized dislocation structures (SODS) in fatigued metals

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