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Title: Yielding transitions and grain-size effects in dislocation theory

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review E
Additional Journal Information:
Journal Volume: 95; Journal Issue: 3; Related Information: CHORUS Timestamp: 2017-04-06 12:00:36; Journal ID: ISSN 2470-0045
American Physical Society (APS)
Country of Publication:
United States

Citation Formats

Langer, J. S. Yielding transitions and grain-size effects in dislocation theory. United States: N. p., 2017. Web. doi:10.1103/PhysRevE.95.033004.
Langer, J. S. Yielding transitions and grain-size effects in dislocation theory. United States. doi:10.1103/PhysRevE.95.033004.
Langer, J. S. Fri . "Yielding transitions and grain-size effects in dislocation theory". United States. doi:10.1103/PhysRevE.95.033004.
title = {Yielding transitions and grain-size effects in dislocation theory},
author = {Langer, J. S.},
abstractNote = {},
doi = {10.1103/PhysRevE.95.033004},
journal = {Physical Review E},
number = 3,
volume = 95,
place = {United States},
year = {Fri Mar 24 00:00:00 EDT 2017},
month = {Fri Mar 24 00:00:00 EDT 2017}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevE.95.033004

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Cited by: 3works
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  • Microstructural attributes of steels affect hysteretic magnetic properties because the microstructure affects domain wall movement and pinning. Two important features are grain size and dislocation density. The consensus experimentally is that the coercivity tends to be linearly related to the inverse of the average grain diameter and to the square root of the dislocation density. In this article, these experimental tendencies are utilized in formulating the dependence of the hysteresis parameters of the Jiles{endash}Atherton model as a function of grain size and dislocation density. The results are then used in computing the first and third harmonics of the magnetic inductionmore » as a function of grain size and dislocation density. This is done via an adaptation of a hysteresis model formulated by Jiles for higher excitation frequencies. The results indicate that the harmonic amplitudes decrease monotonically with inverse grain size and the square root of dislocation density. Since increasing inverse grain size and dislocation density are correlated with increasing tensile strength, the results are consistent with experimental results for the decrease of the harmonic amplitudes with increasing tensile strength in automotive steels. Also, the harmonic amplitudes decrease with increasing excitation frequency, consistent with experiment. {copyright} 2001 American Institute of Physics.« less
  • Grain size effects on the competition between dislocation slip and {101¯2} -twinning in magnesium are investigated using discrete dislocation dynamics simulations. These simulations account for dislocation–twin boundary interactions and twin boundary migration through the glide of twinning dislocations. It is shown that twinning deformation exhibits a strong grain size effect; while dislocation mediated slip in untwinned polycrystals displays a weak one. In conclusion, this leads to a critical grain size at 2.7 μm, above which twinning dominates, and below which dislocation slip dominates.
  • Compression tests have been used to determine the Hall-Petch parameter and the ductility has been measured under tension in three FeCo alloys, Fe-30Co, Fe-50Co and Fe-70Co (compositions given in atomic percent throughout) in both their ordered and disordered states. It was found that disorder, either constitutional or thermal, decreased the Hall-Petch parameter and increased the ductility, results explained by the increased ease of slip transmission on disordering. Surface slip trace observations showed that all the alloys exhibited wavy slip in their disordered states whilst planar slip occurred in the ordered states. The compression tests also showed that Fe-50Co had amore » higher yield strength in the disordered state than in the ordered state, irrespective of grain size, as noted by others. In contrast, irrespective of grain size, the yield strength of Fe-70Co was much lower in the disordered state than in the ordered state. On the other hand, Fe-30Co was stronger in the ordered state at fine grain sizes but weaker at coarse grain sizes. This behavior was interpreted in terms of the short range order upon quenching from 800 C.« less