分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2024-06-11
摘要： Experimental scratch tests and first-principles calculations were used to study the adhesion property of AlCrNbSiTi high-entropy alloy (HEA) coatings on zirconium substrate. AlCrNbSiTi HEA and Cr coatings were deposited on Zr alloy substrates using multi-arc ion plating technology and scratch tests were carried out to estimate adhesion property of the coatings. Scratch test results indicated that Cr coating have a better adhesion strength than HEA coatings, and HEA coatings showed brittleness. The Special quasi-random structure approach was used to build the HEA models, and the models of the Cr/Zr and HEA/Zr interfaces were employed to investigate the cohesion between the coatings and Zr substrate by first-principles calculations. The calculated interface energies showed that the cohesion between Cr coating and Zr substrate is stronger than HEA coatings. Cr, Nb, and Ti in HEA coating, not Al or Si, bind strongly with Zr. Judged by the calculated elastic constants, low Cr content and high Al content will decrease the mechanical performances of the HEA coatings. This work demonstrates the utility of the combined approach involving first-principles calculations and experimental studies for the development of new HEA coating.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2024-03-13
摘要： Cs and I can migrate through the fuel-cladding interface and accelerate the cladding corrosion process induced by the Fuel Cladding Chemical Interaction. Cr coating is an important candidate in mitigating this chemical interaction. First-principles calculations were employed to investigate the diffusion behaviors of Cs and I in Cr bulk and Cr grain boundary, aiming to reveal the microscopic mechanisms for mitigating the interaction at fuel-cladding interface. The interactions between these two fission products and Cr coating were systematically studied, and the temperature-dependent diffusion coeffcients of Cs and I in Cr were obtained using Bocquet’s oversized solute atoms model and Le Claire’s nine-frequency model, respectively. The results show that the migration barriers of Cs and I are significantly lower compared to that of Cr, and the diffusion coeffcients of Cs and I are both more than 3 orders of magnitude larger than Cr self-diffusion coeffcient within the temperature range of Generation IV fast reactors (below 1000 K), which shows the strong penetration ability of Cs and I. Meanwhile, Cs and I are more likely to diffuse along the grain boundary because of the generally low migration barriers, indicating that grain boundary serves as a fast diffusion channel for Cs and I.
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