Molecular Dynamics Study on the Evolution of Primary Irradiation Defects in Uranium-Molybdenum-Niobium Ternary Alloys

摘要: As one of the candidate materials for reactors, uranium alloys face environmental challenges from neutron irradiation during operation. Metal uranium is prone to radiation defects upon irradiation. The addition of metal stabilizers to uranium alloys can enhance their adaptability to the irradiation environment. Among various stabilizers, molybdenum and niobium metals have been extensively studied due to their good solubility and compatibility with metal uranium. In this paper, molecular dynamics methods were employed to simulate the micro-irradiation defect evolution process in the U-Mo-Nb ternary alloy fuel. A potential function suitable for the U-Mo-Nb ternary alloy was trained using machine learning-based approaches. The simulation involves the irradiation cascade damage evolution process under different temperatures, various primary collision atom energies, and incident directions along different lattice vectors, analyzing the impact of different environmental factors on the defect extent of the U-Mo-Nb ternary alloy fuel. The results indicate that the maximum difference in the peak number of defects between the highest and lowest values, depending on the incidence angle, is 7.6%. Higher temperatures lead to a greater number of defect peaks, and fewer defects remain after annealing. The greater the energy of the primary collision atoms, the more defects are produced, and the longer it takes to reach the peak defect number. The number of defects generated in the uranium-molybdenum-niobium ternary alloy under irradiation at similar temperature conditions is approximately 25% that of uranium dioxide, with smaller void and interstitial cluster sizes. Under the impact of primary knock-on atoms with the same energy, the peak number of defects is about 50% of that in the uranium-molybdenum alloy, and the void cluster size is smaller. This indicates that the uranium-molybdenum-niobium ternary alloy has better radiation resistance than uranium-molybdenum alloys, uranium-niobium alloys, and other uranium alloys.