Atomistic simulation of kink-pairs of screw dislocations in body-centred cubic iron |
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| Affiliation: | 1. Department of Computational Materials and Data Science, Sandia National Laboratories, Albuquerque, NM 87185, USA;2. Thermodynamics and Kinetics Group, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA;3. Department of Mechanics of Materials, Sandia National Laboratories, Livermore, CA 94551, USA;4. Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104, USA;1. Dept. of Materials Science and Engineering, University of California Los Angeles, Los Angeles, CA, 90095, USA;2. Dept. of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, CA, 90095, USA |
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| Abstract: | The nudged elastic band method is used to calculate the activation paths connecting jumps between the two degenerate states A and B of the screw dislocation core in body-centred cubic (bcc) iron. Kink-pairs are found to be involved in all such jumps. By comparing the activation energies, it is shown that the jump from state A to state B on the {101} plane is not the same as that from B to A, and whichever is easier depends on the direction of the applied stress. This asymmetry results in a characteristic zigzag pattern of slip, and forms the basis of an explanation for pencil glide at elevated temperatures. The activation energy of the rate-determining jump is found to decrease with increasing stress, but the predicted flow stress is about three times greater than the experimental value at all temperatures. |
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