Atomic-scale insights into influence of rhenium clusters on screw dislocation migration and irradiation hardening in tungsten

WS Yang and CJ Ding and XL Li and ZQ Wang and XY Li and YG Zhang and YC Xu and CS Liu and XB Wu, JOURNAL OF NUCLEAR MATERIALS, 615, 155973 (2025).

DOI: 10.1016/j.jnucmat.2025.155973

In this work, we employed molecular statics and molecular dynamics simulations to investigate the influence of coherent Re clusters on 1/2 < 111> screw dislocation motion in W at the atomic scale. Our results reveal an attractive interaction between Re cluster and the screw dislocation, with interaction strength scaling with cluster size. During dislocation motion, coherent Re clusters (for example, Re clusters with a diameter of 12 & Aring;) acts as effective dislocation traps, requiring the dislocation to overcome an energy barrier (6.7 eV) to escape, which is significantly higher than the Peierls energy barrier in pure W (1.5 eV). Furthermore, Re clusters induce a transition in the kink-pair expansion mechanism of dislocations at the geometric center of Re cluster, shifting from bilateral expansion (observed in pure W and 6-10 & Aring; Re clusters) to unilateral expansion (11-20 & Aring; Re clusters). These clusters also lead to a transformation in the dislocation core structure from symmetric to asymmetric. Finally, through shear simulations, it is found that the CRSS for screw dislocation motion increases with the size of Re clusters (12-50 & Aring; in diameter). Both the calculated migration energy barriers and CRSS values demonstrate that irradiation-induced Re clusters effectively impede the glide of screw dislocations, contributing to irradiation hardening. This work provides an atomic-scale explanation of the effects of irradiation-induced Re clusters on screw dislocation behavior in W, advanced our understanding of the irradiation hardening mechanism in W-based materials.

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