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Title: Two modes of screw dislocation glide in fcc single-phase concentrated alloys

Abstract

Concentrated solid solution alloys (CSSAs), including medium- and high-entropy alloys, are currently being considered as prospective materials in many applications. The behavior of CSSAs under different conditions, including mechanical loading, differs from that of conventional alloys and has been the subject of intensive study by different techniques. In many cases, their behavior is treated by modifying solid solution hardening models, which, in principle, does not reflect many important features of CSSAs where the distinction between solute and solvent atoms is not clear. In this work, we report the results of an atomic-scale study of ½<110>{111} screw dislocation motion in an fcc equiatomic Ni-Fe alloy. Molecular dynamics simulations demonstrate that the dislocation has two distinctive modes for glide. At lower stress, dislocations move in a very rough manner that cannot be described as continuous glide but rather as jerky motion through a set of obstacles. At high stress, they glide in a manner similar to lattice friction-controlled conditions in single component systems. The stress for the transition between modes depends on the dislocation segment length and temperature. As a result, at 300 K, the flow stress saturates at ~130 MPa for lengths above ~140 |b| (b is the Burgers vector).

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Texas A & M Univ., College Station, TX (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1493147
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 164; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Dislocation dynamics; Phonon drag; NiFe alloys; Concentrated alloys; Molecular dynamics

Citation Formats

Osetsky, Yuri N., Pharr, George M., and Morris, James R. Two modes of screw dislocation glide in fcc single-phase concentrated alloys. United States: N. p., 2018. Web. doi:10.1016/j.actamat.2018.11.020.
Osetsky, Yuri N., Pharr, George M., & Morris, James R. Two modes of screw dislocation glide in fcc single-phase concentrated alloys. United States. doi:10.1016/j.actamat.2018.11.020.
Osetsky, Yuri N., Pharr, George M., and Morris, James R. Mon . "Two modes of screw dislocation glide in fcc single-phase concentrated alloys". United States. doi:10.1016/j.actamat.2018.11.020.
@article{osti_1493147,
title = {Two modes of screw dislocation glide in fcc single-phase concentrated alloys},
author = {Osetsky, Yuri N. and Pharr, George M. and Morris, James R.},
abstractNote = {Concentrated solid solution alloys (CSSAs), including medium- and high-entropy alloys, are currently being considered as prospective materials in many applications. The behavior of CSSAs under different conditions, including mechanical loading, differs from that of conventional alloys and has been the subject of intensive study by different techniques. In many cases, their behavior is treated by modifying solid solution hardening models, which, in principle, does not reflect many important features of CSSAs where the distinction between solute and solvent atoms is not clear. In this work, we report the results of an atomic-scale study of ½<110>{111} screw dislocation motion in an fcc equiatomic Ni-Fe alloy. Molecular dynamics simulations demonstrate that the dislocation has two distinctive modes for glide. At lower stress, dislocations move in a very rough manner that cannot be described as continuous glide but rather as jerky motion through a set of obstacles. At high stress, they glide in a manner similar to lattice friction-controlled conditions in single component systems. The stress for the transition between modes depends on the dislocation segment length and temperature. As a result, at 300 K, the flow stress saturates at ~130 MPa for lengths above ~140 |b| (b is the Burgers vector).},
doi = {10.1016/j.actamat.2018.11.020},
journal = {Acta Materialia},
issn = {1359-6454},
number = C,
volume = 164,
place = {United States},
year = {2018},
month = {11}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on November 12, 2019
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