Slip planes in bcc transition metals

Weinberger, Christopher R.; Boyce, Brad Lee; Battaile, Corbett Chandler.

doi:10.1179/1743280412y.0000000015

Cited by 273 publications

(126 citation statements)

References 204 publications

(376 reference statements)

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“…3A shows the plot of critical resolved shear stress (CRSS) at 2% strain as a function of pillar diameter on a log-log scale. We chose the most common slip system in bcc metals, {100}<111> (23), to calculate CRSS for all experiments by multiplying the axial flow stress at 2% strain by the maximum Schmidt factor allowed for the slip system. The crystallographic orientation of each pillar was estimated either directly from electron backscatter diffraction (EBSD) map or from the unloading data when EBSD mapping was unavailable (details given in Supporting Information).…”

mentioning

confidence: 99%

Enhanced strength and temperature dependence of mechanical properties of Li at small scales and its implications for Li metal anodes

Ahmad

Aryanfar

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

232

191

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Most next-generation Li ion battery chemistries require a functioning lithium metal (Li) anode. However, its application in secondary batteries has been inhibited because of uncontrollable dendrite growth during cycling. Mechanical suppression of dendrite growth through solid polymer electrolytes (SPEs) or through robust separators has shown the most potential for alleviating this problem. Studies of the mechanical behavior of Li at any length scale and temperature are limited because of its extreme reactivity, which renders sample preparation, transfer, microstructure characterization, and mechanical testing extremely challenging. We conduct nanomechanical experiments in an in situ scanning electron microscope and show that micrometer-sized Li attains extremely high strengths of 105 MPa at room temperature and of 35 MPa at 90°C. We demonstrate that single-crystalline Li exhibits a power-law size effect at the micrometer and submicrometer length scales, with the strengthening exponent of −0.68 at room temperature and of −1.00 at 90°C. We also report the elastic and shear moduli as a function of crystallographic orientation gleaned from experiments and first-principles calculations, which show a high level of anisotropy up to the melting point, where the elastic and shear moduli vary by a factor of ∼4 between the stiffest and most compliant orientations. The emergence of such high strengths in small-scale Li and sensitivity of this metal's stiffness to crystallographic orientation help explain why the existing methods of dendrite suppression have been mainly unsuccessful and have significant implications for practical design of future-generation batteries.dendrite | size effect | elastic anisotropy | dislocation | elevated temperature I ncreased adoption of electric vehicles requires an improvement in the energy density of rechargeable Li ion batteries. Li metal anode is a common and necessary ingredient in commercialization pathways for next-generation Li ion batteries. In the near term, Li metal coupled with an advanced cathode could lead to a specific energy of 400 Wh/kg at the cell level, which represents 200% improvement over current state of the art (1). In the longer term, Li metal coupled with a S and O 2 cathode could lead to even higher specific energies of >500 Wh/kg. Despite over 40 y of research, overcoming the uncontrollable dendrite growth during cycling has remained an insurmountable obstacle for Li-based components (2). Among multiple attempted approaches to eliminate or even reduce the dendrite growth, mechanical suppression has emerged as one of the most promising routes. In their pioneering theoretical work, Monroe et al. (3) considered a solid polymer electrolyte (SPE) in contact with a Li metal electrode and performed a linear stability analysis of the deformation at the interface. They used linear elasticity to compute the stresses generated at the interface due to small deformations. They found that the dendrite growth decays with time if the shear modulus of the SPE is higher than about t...

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mentioning

confidence: 99%

Enhanced strength and temperature dependence of mechanical properties of Li at small scales and its implications for Li metal anodes

Ahmad

Aryanfar

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

232

191

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“…37 Therefore, we improved the fatigue prognosis based on a non-local data mining procedure along potential crack paths aligned with the available 〈111〉 crystallographic slip directions. 38 This echoes the pencil-glide deformation mechanics observed in other BCC alloys 26,27,39 ; although the spatial resolution available in this work (slightly below a micrometer), ultimately limits the microscopic failure mechanism determination. A similar approach is used in this work but considering multiple micromechanical and microstructural variables to first predict the crack path and then the associated speed of crack propagation.…”

Section: Introductionmentioning

confidence: 79%

Using machine learning and a data-driven approach to identify the small fatigue crack driving force in polycrystalline materials

Rovinelli¹,

Sangid²,

Proudhon³

et al. 2018

npj Comput Mater

142

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The propagation of small cracks contributes to the majority of the fatigue lifetime for structural components. Despite significant interest, criteria for the growth of small cracks, in terms of the direction and speed of crack advancement, have not yet been determined. In this work, a new approach to identify the microstructurally small fatigue crack driving force is presented. Bayesian network and machine learning techniques are utilized to identify relevant micromechanical and microstructural variables that influence the direction and rate of the fatigue crack propagation. A multimodal dataset, combining results from a high-resolution 4D experiment of a small crack propagating in situ within a polycrystalline aggregate and crystal plasticity simulations, is used to provide training data. The relevant variables form the basis for analytical expressions thus representing the small crack driving force in terms of a direction and a rate equation. The ability of the proposed expressions to capture the observed experimental behavior is quantified and compared to the results directly from the Bayesian network and from fatigue metrics that are common in the literature. Results indicate that the direction of small crack propagation can be reliably predicted using the proposed analytical model and compares more favorably than other fatigue metrics.

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“…Further experimental investigations have confirmed the complex nature of slip as a characteristic feature of all bcc metals and established that the h111i screw dislocations control the plastic flow rate in bcc metals and that they glide by the thermally activated generation and motion of kinkpairs [5]. However, the elementary slip planes on which dislocations glide are still unresolved (see [6] for a recent review on the slip planes in bcc metals).…”

Section: Introductionmentioning

confidence: 88%

Dislocation junctions as indicators of elementary slip planes in body-centered cubic metals

2014

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In body-centered cubic (bcc) metals, an unambiguous determination of the elementary slip planes remains difficult owing to several possible interpretations of the glide activity, of slip steps on the specimen surface or features of the dislocation microstructure. In this article, a method is proposed to determine the elementary slip planes in bcc metals based on the line directions of sessile junctions resulting from the interaction of mobile dislocations with (Formula presented.) Burgers vector. The proposed method allows to determine slip activity inside a material and not at its surface, where other effects may play a role. It is in principle applicable to determining the elementary slip plane in any crystalline material. Particularly, it may help to resolve a long-standing debate of the nature of the elementary slip planes in bcc metals

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Slip planes in bcc transition metals

Cited by 273 publications

References 204 publications

Enhanced strength and temperature dependence of mechanical properties of Li at small scales and its implications for Li metal anodes

Enhanced strength and temperature dependence of mechanical properties of Li at small scales and its implications for Li metal anodes

Using machine learning and a data-driven approach to identify the small fatigue crack driving force in polycrystalline materials

Dislocation junctions as indicators of elementary slip planes in body-centered cubic metals

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