Kinetics of interstitial defects in alpha-Fe: The effect from uniaxial stress

CW Kang and QY Wang and L Shao, JOURNAL OF NUCLEAR MATERIALS, 485, 159-168 (2017).

DOI: 10.1016/j.jnucmat.2016.12.015

Understanding defect kinetics in a stress field is important for multiscale modeling of materials degradation of nuclear materials. By means of molecular dynamics and molecular statics simulations, we calculate formation and migration energies of self-interstitial atoms (SIA) and SIA clusters (up to size of 5 interstitials) in alpha Fe and identify their stable configurations under uniaxial tensile strains. By applying uniaxial stress along 111, < 111 > oriented single SIA defects become more stable than < 110 > oriented SIA, which is opposite to stress-free condition. Diffusion of single SIA defects under 111 tensile stress is facilitated along 111 direction and the diffusion becomes one dimensional (1D). For SIA clusters, their diffusion under zero stress has gradual transition from three dimensional (3D) for small clusters to one dimensional (1D) for large clusters. Under the tensile Stress along 111, the 3D to 1D transition is accelerated. For large SIA clusters, the stress effect is quickly saturated with less diffusivity enhancement in comparison with small SIA clusters. (C) 2016 Elsevier B.V. All rights reserved.

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