离子辐照/LBE腐蚀协同作用引起铁铬基合金结构演化的机理研究

Structural components served in nuclear reactors always endure extreme conditions of intensive high energy neutron irradiations and coolant erosions. Such severe environments will cause microstructural changes and macro property degradations of materials used for these structural components, thus affect safe operations of the nuclear reactor. The structure and property evolutions of materials under synergetic effects of intensive high energy neutron irradiations and coolant erosions have drawn extensive attentions worldwide, and are one of the key issues needed to be solved urgently for research and development (R&D) of future advanced nuclear reactors. In this study, candidate materials iron chromium based alloys for lead cooled fast reactor, which is a generation IV nuclear energy system, will be selected to simulate the synergetic effects of neutron irradiations and coolant erosions. The irradiation and erosion experiments will be conducted at one of the Heavy Ion Research Facility at Lanzhou (HIRFL) terminals, which couples erosions of Lead Bismuth Eutectic (LBE) with controlled oxygen content to ion irradiations. Combined with computer simulations, multiple measurement and analysis methods will be employed to extensively investigate oxide film formation and evolution of the iron chromium based alloys under different irradiation doses with controlled oxygen LBE conditions. Special attentions will be paid to the synergetic effects of irradiations and erosions on the formation and growth dynamics of the oxide film. Based on this investigation, we are aiming at revealing mechanisms of the oxide film destabilization and near surface microstructure evolutions of materials under the synergetic effects of irradiations and LBE erosions, thus establishing a method to estimate and predict the candidate materials properties under synergetic effects of intensive high energy neutrons and coolant erosions. These results can also provide basic scientific rules and databases for R&D and selections of both irradiation and erosion resistant materials for our future advanced nuclear reactor systems.

反应堆内构件长期在强中子辐照、冷却剂腐蚀等极端环境条件下服役，构件材料会发生微结构变化与宏观性能恶化失效进而影响反应堆的运行安全。强中子辐照和冷却剂腐蚀协同作用条件下材料结构和性能演化问题在国际上备受关注，是未来先进反应堆研发面临的迫切需要解决的关键问题之一。本项目选择铅冷快堆用候选材料铁铬基合金为研究对象，依托HIRFL控氧LBE腐蚀/离子辐照协同作用效应实验装置开展实验，采用多种分析手段测试分析实验样品，结合计算机模拟，深入研究不同辐照损伤水平、控氧LBE腐蚀条件下铁铬基合金材料氧化膜的生成与演化，特别是离子辐照/LBE腐蚀协同作用下材料氧化膜形成及生长动力学规律，揭示辐照/LBE腐蚀协同作用下氧化膜的失稳机制和材料近表面结构演化机理，为评价和预测强中子辐照/腐蚀协同作用条件下候选材料的使役性能并为我国未来先进核能系统用抗辐照耐腐蚀材料的研发和选择应用提供重要的科学依据和数据支撑。

铅冷快堆（LFR）构件长期在强中子辐照、冷却剂腐蚀等极端环境条件下服役，构件材料会发生微结构变化与宏观性能恶化失效进而影响反应堆的运行安全。强中子辐照和冷却剂腐蚀协同作用条件下材料结构和性能演化问题是未来先进反应堆研发面临的迫切需要解决的关键问题之一。本项目选择铅LFR用候选材料铁铬基合金为研究对象，围绕科学问题，依托合作单位的各自的专业优势和特长，紧密协助，获得如下研究进展和成果：.1. 制备了50公斤级，不同Si或Al含量的FeCr合金。在此基础上，系统研究了含Si/Al的FeCr基合金在液态铅铋中腐蚀效应及机制。研究表明，Si或Al元素可以促使在FeCr基合金表面形成富Si/Al氧化膜，阻止LBE向基体渗透及合金元素溶解，从而提高了材料的耐腐蚀性能，此外，Si和Mo在抗氧化过程中存在协同作用，Mo元素可以协助Si元素提高抗液态金属腐蚀的能力。.2. 利用兰州重离子加速器提供的高能重离子束，依托国内唯一的重离子辐照与LBE腐蚀协同作用实验装置，在SIMP钢中开展了协同效应研究。研究表明，离子辐照不仅显著加速了液态铅铋腐蚀效应，而且也显著改变了表面腐蚀层微观结构。初步研究认为，辐照增强元素扩散是引起协同效应的主要的机制。.3. 应用多种模拟软件研究了铁基合金表面液态金属腐蚀特性和辐照损伤特性，以及基体微结构（表面/晶界）、合金元素和辐照缺陷对腐蚀的能量学和动力学特性的影响，揭示服役环境下SIMP钢液态金属腐蚀和辐照损伤的微观机制。在此基础上，发展Fe-Pb二元和Fe-Pb-O三元势函数，以及铁基材料辐照损伤和液态金属腐蚀的蒙特卡洛程序，为深入研究液态金属腐蚀和辐照损伤协同作用奠定了基础。.在本项目执行期间，共发表SCI论文21篇，登记2项软件著作权，授权2项技术发明专利，邀请报告5人次。项目共培养博士研究生3人，硕士研究生3名，己经完成了项目制定的研究目标。