Assessment of elastic anisotropy and incipient plasticity in Fe<sub>3</sub>C by nanoindentation

Alkorta, Jon; Sevillano, J. Gil

doi:10.1557/jmr.2011.284

Cited by 26 publications

(19 citation statements)

References 43 publications

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“…[22][23][24] Elastic moduli measured at 300K do not exhibit the extreme shear anisotropy reported from 0K DFT calculations. 25,26 Our measurements of the Fe pDOS indicate that the acoustic modes stiffen significantly with temperature below the magnetic transition, suggesting significant temperature-driven changes to the elastic constants.…”

Section: Elastic Constantsmentioning

confidence: 76%

“…23 The limited number of experimental studies of elastic behavior report that cementite does appear anisotropic, but not to the extent predicted by density functional theory. 25,26 An ultrasonic study of the elastic properties of Fe 3 C reported anomalous thermal behavior at low temperatures. 27 The anisotropic elastic behavior of cementite is likely linked to its complex anisotropic magneto-volume behavior.…”

Section: -15mentioning

confidence: 99%

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Phonons and elasticity of cementite through the Curie temperature

et al. 2017

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Phonon partial densities of states (pDOS) of 57 Fe3C were measured from cryogenic temperatures through the Curie transition at 460K using nuclear resonant inelastic x-ray scattering. The cementite pDOS reveal that low-energy acoustic phonons shift to higher energies (stiffen) with temperature before the magnetic transition. This unexpected stiffening suggests strongly nonharmonic vibrational behavior that impacts the thermodynamics and elastic properties of cementite. Density functional theory (DFT) calculations reproduced the anomalous stiffening observed experimentally in cementite by accounting for phonon-phonon interactions at finite temperatures. The calculations show that the low-energy acoustic phonon branches with polarizations along the [010] direction are largely responsible for the anomalous thermal stiffening. The effect was further localized to the motions of the FeII site within the orthorhombic structure, which participates disproportionately in the anomalous phonon stiffening.

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Section: Elastic Constantsmentioning

confidence: 76%

Section: -15mentioning

confidence: 99%

Phonons and elasticity of cementite through the Curie temperature

et al. 2017

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“…anisotropy. The slightly overestimated anisotropy of the microstrain broadening given by the predicted value of A " may be the result of an overestimated elastic anisotropy from the first-principles calculations, which pertain to 0 K. Indeed, recent nano-indentation experiments confirm the existence of the elastic anisotropy of (alloying-element-containing) Fe 3 C, but also suggest that the theoretically predicted elastic constants may exhibit an overestimated anisotropy (Alkorta & Sevillano, 2012).…”

Section: Comparison Between Predicted Microstrain Distribution and Exmentioning

confidence: 86%

Anisotropic microstrain broadening in cementite, Fe₃C, caused by thermal microstress: comparison between prediction and results from diffraction-line profile analysis

Leineweber

2012

J Appl Cryst

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X-ray powder diffraction data of an Fe 3 C powder consisting of polycrystalline particles shows pronouncedly anisotropic microstrain broadening of the Bragg reflections. The extent and anisotropy of the broadening can quantitatively be attributed to thermal microstresses induced by anisotropic thermal shrinkage from the preparation temperature of 873 K to the ambient analysis temperature, in conjunction with the elastic anisotropy of Fe 3 C. research papers J. Appl. Cryst. (2012). 45, 944-949 A. Leineweber Anisotropic microstrain broadening in cementite 945 research papers J. Appl. Cryst. (2012). 45, 944-949 A. Leineweber Anisotropic microstrain broadening in cementite 949

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“…If then s 2323 might be overestimated by the DFT calculation, the predicted ½hðÁ" hkl Þ 2 i 1=2 calculated using the 'true', smaller s 2323 would be significantly smaller, as the s ijpq -containing sum in equation (20) would be lower. Nanoindentation experiments on cementite by Alkorta & Sevillano (2012) suggest that the elastic anisotropy of cementite might indeed be overestimated by the DFT calculations, implying mainly a smaller 'true' s 2323 . However, if in the calculations c 2323 is increased by a factor of two, 4 the predicted values of ½hðÁ" hkl Þ 2 i 1=2 decrease only by about 20%, which is unable to completely explain the observed disagreement between measured and predicted values.…”

Section: Discrepancies Between Measured Data and Predictionsmentioning

confidence: 95%

Thermal expansion anisotropy as source for microstrain broadening of polycrystalline cementite, Fe₃C

Leineweber¹

2016

J Appl Cryst

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Cementite (Fe3C) powder consisting of polycrystalline particles was investigated by synchrotron X‐ray diffraction and neutron diffraction at temperatures between 10 and 973 K. The data reveal a pronouncedly anisotropic thermal expansion of the orthorhombic unit cell as well as microstrain broadening varying considerably with temperature. Using a theory for predicting thermal‐microstress‐induced microstrain already applied in previous work to ambient‐temperature sealed‐tube X‐ray powder diffraction data from the same material [Leineweber (2012). J. Appl. Cryst.45, 944–949], the temperature‐dependent extent of the measured microstrain broadening could be quantitatively related to the measured temperature‐dependent anisotropy of the thermal expansion. Thereby, the fact that the extent of the measured microstrain broadening is somewhat smaller than the predicted amount can be explained by the presence of the free surfaces of the powder particles reducing the level of microstress‐induced microstrain.

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Assessment of elastic anisotropy and incipient plasticity in Fe₃C by nanoindentation

Abstract: Abstract

Cited by 26 publications

References 43 publications

Phonons and elasticity of cementite through the Curie temperature

Phonons and elasticity of cementite through the Curie temperature

Anisotropic microstrain broadening in cementite, Fe₃C, caused by thermal microstress: comparison between prediction and results from diffraction-line profile analysis

Thermal expansion anisotropy as source for microstrain broadening of polycrystalline cementite, Fe₃C

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Assessment of elastic anisotropy and incipient plasticity in Fe3C by nanoindentation

Abstract: Abstract

Cited by 26 publications

References 43 publications

Phonons and elasticity of cementite through the Curie temperature

Phonons and elasticity of cementite through the Curie temperature

Anisotropic microstrain broadening in cementite, Fe3C, caused by thermal microstress: comparison between prediction and results from diffraction-line profile analysis

Thermal expansion anisotropy as source for microstrain broadening of polycrystalline cementite, Fe3C

Contact Info

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Resources

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Assessment of elastic anisotropy and incipient plasticity in Fe₃C by nanoindentation

Anisotropic microstrain broadening in cementite, Fe₃C, caused by thermal microstress: comparison between prediction and results from diffraction-line profile analysis

Thermal expansion anisotropy as source for microstrain broadening of polycrystalline cementite, Fe₃C