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Abstract: The characteristics of intrinsic defects are important for the understandingof self-diffusion processes, mechanical strength, brittleness, and plasticityof tungsten carbide, which present in the divertor of fusion reactors. Here, weuse first-principles calculations to investigate the stability of point defectsand their complexes in WC. Our calculation results confirm that the formationenergies of carbon defects are much lower than that of tungsten defects. Theoutward relaxations around vacancy are found. Both interstitial carbon andinterstitial tungsten atom prefer to occupy the carbon basal plane projectionof octahedral interstitial site. The results of isolated carbon defectdiffusion show that the carbon vacancy stay for a wide range of temperaturebecause of extremely high diffusion barriers, while carbon interstitialmigration is activated at lower temperatures for its considerable loweractivation energy. These results provide evidence for the presumption that the800K stage is attributed by the annealing out of carbon vacancies by long-rangemigration.



Author: Xiang-Shan Kong 1, Yu-Wei You 1, J. H. Xia 1, C. S. Liu 1, Q. F. Fang 1, G.-N. Luo 2, Qun-Ying Huang 2 1 Key Laboratory of Materi

Source: https://arxiv.org/







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