Temperature and orientation effects on the deformation mechanisms of α-Fe micropillars

Hagen, Anette Brocks; Snartland, Brage Dahl; Thaulow, Christian

doi:10.1016/j.actamat.2017.03.006

Cited by 52 publications

(20 citation statements)

References 47 publications

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“…During compressive deformation of <100> BCC Fe nanowires, it has been shown that dislocationmediated plasticity dominates at 500 K, whereas the twinning mechanism has been observed in addition to the dislocation slip at lower temperatures 20 . A similar behavior has been observed with respect to temperature in <110> BCC Fe nanowires 10 .…”

Section: Introductionsupporting

confidence: 82%

“…Further, it has been shown that BCC Fe nanowires exhibit tension-compression asymmetry in deformation mechanisms 8,9 . In contrast to tensile loading, the nanowire with <100> orientation deformed by the dislocation slip, whereas twinning was observed in <110> orientation under compressive loading [8][9][10] . Recently, Wang et al 11 have provided the first experimental evidence of deformation twinning in BCC W nanowires with 15 nm diameter thereby conforming the predictions made using MD simulations.…”

Section: Introductionmentioning

confidence: 98%

“…Most of these studies in BCC metallic nanowires have been focused mainly on deformation aspects such as twinning and dislocation behavior [8][9][10][11][12][13][14][15][16][17][18][19][20] . It is surprising that enough attention has not been paid towards the fracture behavior of BCC Fe nanowires.…”

Section: Introductionmentioning

confidence: 99%

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Atomistic simulations on ductile-brittle transition in ⟨111⟩ BCC Fe nanowires

Sainath

Choudhary

2017

Journal of Applied Physics

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Molecular dynamics simulations have been performed to understand the influence of temperature on the tensile deformation and fracture behavior of <111> BCC Fe nanowires. The simulations have been carried out at different temperatures in the range 10-1000 K employing a constant strain rate of 1× 10 8 s −1 . The results indicate that at low temperatures (10-375 K), the nanowires yield through the nucleation of a sharp crack and fails in brittle manner. On the other hand, nucleation of multiple 1/2<111> dislocations at yielding followed by significant plastic deformation leading to ductile failure has been observed at high temperatures in the range 450-1000 K. At the intermediate temperature of 400 K, the nanowire yields through nucleation of crack associated with many mobile 1/2<111> and immobile <100> dislocations at the crack tip and fails in ductile manner. The ductile-brittle transition observed in <111> BCC Fe nanowires is appropriately reflected in the stress-strain behavior and plastic strain at failure. The ductile-brittle transition increases with increasing nanowire size. The change in fracture behavior has been discussed in terms of the relative variations in yield and fracture stresses and change in slip behavior with respect to temperature. Further, the dislocation multiplication mechanism assisted by the kink nucleation from the nanowire surface observed at high temperatures has been presented.

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Section: Introductionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 98%

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Atomistic simulations on ductile-brittle transition in ⟨111⟩ BCC Fe nanowires

Sainath

Choudhary

2017

Journal of Applied Physics

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“…This approach opens an opportunity to experimentally confirm the assumed mechanism of the improved room temperature ductility of the 18Cr ferritic stainless steels by adding the stabilizing elements. However, there are a few reports on micropillar compression tests applied for ferrous materials, [18][19][20][21] regardless of various reports on single-crystal micropillars of pure bcc metals (Cr, Nb, W and Ta). [22][23][24][25][26][27][28] In micro-mechanical testing, size-dependent strength of microscale specimens (smaller is stronger) is generally known in bcc pure metals.…”

Section: Strain Rate Sensitivity Of Flow Stress Measured By Micropillmentioning

confidence: 99%

“…22,27) However, the strength of ferrous materials measured by micro-mechanical testing has been scarcely reported. 20) Furthermore, the strain rate sensitivity of flow stress of ferritic steels could significantly influence the fracture toughness controlling the room temperature ductility, [11][12][13] whereas there is no literature on the effect of strain rate on mechanical response of micro-scale steel specimens.…”

Section: Strain Rate Sensitivity Of Flow Stress Measured By Micropillmentioning

confidence: 99%

Strain Rate Sensitivity of Flow Stress Measured by Micropillar Compression Test for Single Crystals of 18Cr Ferritic Stainless Steel

Tianqi

Takata

et al. 2020

ISIJ Int.

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We have fabricated cylindrical single-crystal micropillars with different diameter (d) ranges of 2-3 μm and 5-6 μm on a specific grain in the 18Cr ferritic stainless steel with a ferrite single-phase microstructure. The initial strain rate at the onset of plastic deformation was controlled by variable loading rate in the used nanoindenter. The strain rate sensitivity of the stress required for the slip initiation were examined using the fabricated micropillars. The present compression tests addressed the shear stress on an activated single slip system of micron-scale single-crystals. Smaller-sized micropillars (d = 2-3 μm) often exhibit intermittent strain bursts. The stress for slip initiation (after an elastic loading) changes depending on the initial strain rate, resulting in a high strain rate sensitivity (m) of 0.12. Larger-sized micropillars (d = 5-6 μm) show a continuous yielding. A slight change in their yield stress depending on the initial strain rate provides a relatively low m of 0.04. It is similar to one of the millimeter-sized specimens measured by conventional tensile tests. These results provide new insights to optimize the specimen size for the micropillar compression test applied for the 18Cr ferritic stainless steels.

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Molecular Dynamics Simulations on the Mechanical Behavior of AlCoCrCu0.5FeNi High-Entropy Alloy Nanopillars

Tang

Wang

et al. 2019

The Minerals, Metals &Amp; Materials Series

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Temperature and orientation effects on the deformation mechanisms of α-Fe micropillars

Cited by 52 publications

References 47 publications

Atomistic simulations on ductile-brittle transition in ⟨111⟩ BCC Fe nanowires

Atomistic simulations on ductile-brittle transition in ⟨111⟩ BCC Fe nanowires

Strain Rate Sensitivity of Flow Stress Measured by Micropillar Compression Test for Single Crystals of 18Cr Ferritic Stainless Steel

Molecular Dynamics Simulations on the Mechanical Behavior of AlCoCrCu0.5FeNi High-Entropy Alloy Nanopillars

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