乏燃料贮运用抗辐照铁基非晶合金的形成机理

With the increasing numbers of nuclear power plants are built and put into operation, more and more spent nuclear fuels are produced. Therefore it is imperious to develop high performance material for storage and transportation of these spent nuclear fuels to keep the health of human being and the ecological safty. This propgram is proposed to focus on the the nature of the radiation resistance and the formation mechanism of the Fe-base amorphous alloys. In this program, we chose the supersonic atomization equipment as the technological protype. By using the ab initio molecular dynamics and empirial molecular dynamics calculations, in situ synchrotron radiation technology as well as heavy ions irradiation simulations, the relation among the the intrinsic characteristics of elements, local ordering and radiation resistance are studied. The nucleation and evolution of defects under irradiation conditions for the high boron content Fe-base amorphous alloys would be investigated systematically. By analyzing the local order of amorphous alloys and measuring the thermodynamical properties including the internal energy, heat capacity and free energy, the formation theory of high boron contaning Fe-based amorphous alloys is proposed. The technological basis for the preparation of supersonic atomization is established by the investigation of heat and mass transfer and the solidification behaviors for Fe based amorphous alloys. The failure mechanism will be clerified after the investigation of the variation of structure and properties of these amorphous alloys under the irradiation and corrosion conditions. As the above studies are completed, a systematic theory involving irradiation resistance, glass forming ability and rapid solidification preparation will be established. It is believed that this programe will provide guidence for the practical application of amorphous alloys in the storage and transportation of the spent nuclear fuels.

我国未来将有多座核电站建成和投入运营，产生的乏燃料会越来越多，因此急需发展高性能乏燃料贮运材料以保证人类和生态安全。项目以高抗辐照能力Fe基非晶合金为对象，以超音速雾化制备过程为技术原型，利用第一性原理和分子动力学计算、同步辐射测量以及重离子轰击等方法，系统研究高B含量Fe基非晶合金中元素本征特性和局域有序结构与抗辐照能力关系，以及辐照缺陷的产生和演变过程，揭示非晶合金抗辐照性能的本质。通过对非晶合金局域有序结构的解析，及内能、比热和自由能等热力学参数的测定，提出高B含量Fe基非晶合金的形成理论。基于快速凝固条件下非晶合金传热传质和凝固行为的研究，建立非晶合金超音速雾化制备工艺理论基础。根据辐照和腐蚀作用下Fe基非晶合金结构和性能变化，阐明其辐照失效机理。项目完成后，将建立以抗辐照效应-非晶形成能力-快速凝固制备基础为主线的非晶形成理论体系，为该非晶合金在乏燃料贮运材料中的应用奠定基础。

本项目以发展新型高硼耐蚀抗辐照铁基块体非晶合金为目标，对Fe基块体非晶合金进行了优化设计，研制了新型Fe-Cr-Mo-C-B-Al-W和高硼高铬Fe-Cr-Mo-Zr-B块体非晶合金体系。系统研究了新型非晶合金的力学性能和腐蚀行为；以超音速气雾化制备和超音速火焰喷涂过程为技术原型，制备了Fe-Cr-Mo-Zr-B非晶合金涂层，系统研究了非晶合金涂层的力学、耐腐蚀以及抗辐照性能。取得了如下创新性结果：.(1) 获得了非晶形成能力好和高硼含量Fe-Cr-Mo(W, Al)-C-B-Y块体非晶合金。该合金压缩强度和显微硬度分别超过4GPa和300HV，在盐酸中具有优异的耐蚀性能。(2) 研制出了新型Fe-Cr-Mo-Zr-B系块体非晶合金。该合金系具有宽铬、硼和钼含量变化范围，具有高强度、高硬度和耐磨性，能够满足多种服役环境需求。(3) 系统研究了Fe-Cr-Mo-Zr-B系块体非晶合金在盐酸溶液中的耐腐蚀性能，发现了铬含量控制的活性-惰性转变现象，揭示了决定耐蚀非晶合金低铬临界值的内在机理。提出了通过钼的添加实现耐蚀性转变调控，从而获得超级不锈特性的新思路。(4) 对优选的高铬、高硼和低钼非晶合金进行了气雾化制粉和超音速火焰喷涂，建立了非晶合金设计—非晶粉末制备—HVOF法制备非晶涂层的完整工艺流程，实现了非晶合金形成与快速凝固的实践与理论统一；所制备的Fe54Cr18Mo2Zr8B18 非晶涂层的结合强度达到了迄今为止的最高值，其耐磨耐腐蚀性大大优于商业非晶合金涂层，在盐酸和模拟海水中的耐蚀性显著优于304不锈钢。(5) 制备出了具有优异抗重离子辐照性能的新型Fe基非晶合金及其涂层，并阐明了该非晶合金涂层具有优异抗辐照特性的原因。实验证明，本项目研制的非晶合金涂层的抗辐照性能显著优于商业非晶合金涂层。(6) 在国际上报导了首个四元Cr基块体非晶合金体系，该合金具有极高的硬度、弹性模量以及优异的耐腐蚀性能。.上述成果对于发展我国核工业和耐磨防腐等领域使用的新型钢铁材料具有重要理论指导意义。在项目支持下，我们在Acta Materialia和Corrosion Science等国际学术期刊上发表论文27篇，均为SCI收录，授权国家发明专利2项，公开1项。培养国家优秀青年基金获得者1名，毕业博士硕士生6名。承办和参加国际学术会议和邀请外国专家来华交流达20人次以上。