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Title: Defect-induced change of temperature-dependent elastic constants in BCC iron

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 490; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 15:32:21; Journal ID: ISSN 0022-3115
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Citation Formats

Gao, N., Setyawan, W., Zhang, S. H., and Wang, Z. G. Defect-induced change of temperature-dependent elastic constants in BCC iron. Netherlands: N. p., 2017. Web. doi:10.1016/j.jnucmat.2017.04.005.
Gao, N., Setyawan, W., Zhang, S. H., & Wang, Z. G. Defect-induced change of temperature-dependent elastic constants in BCC iron. Netherlands. doi:10.1016/j.jnucmat.2017.04.005.
Gao, N., Setyawan, W., Zhang, S. H., and Wang, Z. G. Sat . "Defect-induced change of temperature-dependent elastic constants in BCC iron". Netherlands. doi:10.1016/j.jnucmat.2017.04.005.
title = {Defect-induced change of temperature-dependent elastic constants in BCC iron},
author = {Gao, N. and Setyawan, W. and Zhang, S. H. and Wang, Z. G.},
abstractNote = {},
doi = {10.1016/j.jnucmat.2017.04.005},
journal = {Journal of Nuclear Materials},
number = C,
volume = 490,
place = {Netherlands},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.jnucmat.2017.04.005

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  • The effects of radiation-induced defects (randomly distributed vacancies, voids, and interstitial dislocation loops) on temperature-dependent elastic constants, C11, C12, and C44 in BCC iron, are studied with molecular dynamics method. The elastic constants are found to decrease with increasing temperatures for all cases containing different defects. The presence of vacancies, voids, or interstitial loops further decreases the elastic constants. For a given number of point defects, the randomly distributed vacancies show the strongest effect compared to voids or interstitial loops. All these results are expected to provide useful information to combine with experimental results for further understanding of radiation damage.
  • Using molecular dynamics calculations we demonstrate that with decreasing the thickness of ultrathin body-centered-cubic (bcc) {alpha}-Fe film with (001) surfaces, the biaxial strain results in first bcc(001){yields}face-centered-cubic (fcc) (001) transition along the inverse Bain path due to softening of C{sub 33}, and then fcc(001){yields}bcc(011) because of shear modulus vanishing along fcc <110> directions. For the bulk fcc {gamma}-Fe, the tensile biaxial strain along the Bain path transforms fcc (001) into bcc (001) with fcc<110> parallel bcc<100>, while compressive strain results in shear instability, in agreement with recent ab initio calculations.
  • First-principles total energy calculation based on the exact muffin-tin orbital and full potential linear muffin-tin orbital methods were used to calculate the equation of state and shear elastic constants of bcc V, Nb, and the V{sub 95}Nb{sub 05} disordered alloy as a function of pressure up to 6 Mbar. We found a mechanical instability in C{sub 44} and a corresponding softening in C at pressures {approx} 2 Mbar for V. Both shear elastic constants show softening at pressures {approx} 0.5 Mbar for Nb. Substitution of 5 at. % of V with Nb removes the instability of V with respect tomore » trigonal distortions in the vicinity of 2 Mbar pressure, but still leaves the softening of C{sub 44} in this pressure region. We argue that the pressure induced shear instability (softening) of V (Nb) originates from the electronic system and can be explained by a combination of the Fermi surface nesting, electronic topological transition, and band Jahn-Teller effect.« less
  • Values of the elastic constants of single crystals of the bcc transition elements vanadium, niobium, and tantalum are reported at T = 27 deg C. They are, in units of 10/sup 11/ d/cm/sup 2/ for c/sub 11/, c/sub 12/, and c/sub 44/: V- 22.8, 11.9, 4.26; Nb- 24.6, 13. 2.87; and Ta-26.7, 16.1, 8.25, respectively. Comparisons are made of the values obtained for two crystals each of vanadium and tantalum. A high-frequency cw resonance technique was used in the measurements. The shear anisotropies A = 2c/sub 44//(c/sub 11/ - c/sub 12/) are anomalously small for these elements as compared tomore » other cubic system elements. An analysis of the shear anisotropy, based on Fuchs' model, is given. It is found essential to consider next-nearest as well as nearest-neighbor ion-ion interactions. (auth)« less