铝基碳化硼材料半固态复合与流变轧制组织形成机理

With the rapid development of the nuclear industry, the processing of spent fuel and nuclear waste has become a major problem of the world. Intensive intermediate storage rack is usally adopted for the storage of spent fuel in the world. The isolation block that has strong neutron absorption ability is filled in the irradiated fuel assembly. Aluminum boron carbide composite material as an isolated block can meet the design requirements of at least 50 years storage time recommended by the International Atomic Energy Agency, so the potential economic and social benefits are huge. But the preparation and processing of the material have the following problems: ① the preparation process is complex and long; ② due to the poor wettability, the boron carbide reunion is serious. In this proposal, a more efficient and short process for preparing aluminum boron carbide composite plate is given based on combining the semisolid synthesizing and rheorolling. This proposal will focus on the following points: the effects of surface activation and alloy composition on activation properties of boron carbide and interfacial bonding performance; the interface bonding mechanism and dispersion mechanism of boron carbide under actions of shearing/stirring; the effects of shearing/vibration on the primary solid phase and homogeneity of aluminum boron carbide composite slurry; microstructure forming mechanism of aluminum boron carbide composite during rheorolling. The outputs of this study could provide theoretical guidance for the establishment of short manufacturing process of aluminum boron carbide composite plate.

随着世界核工业迅速发展，乏燃料及核废料处理已成为全球所面临的重大关键问题。国际上采用密集型中间储存架存储乏燃料，在乏燃料组件之间填充具有强中子吸收能力的隔离块。铝基碳化硼复合材料作为隔离块可满足国际原子能机构推荐的至少50年储存时间的设计要求，潜在巨大的经济和社会效益。但是目前该材料的制备及加工存在如下问题：①制备工艺复杂，流程长。②碳化硼界面润湿差，团聚严重。 为此，本项目提出铝基碳化硼材料半固态复合方法与流变轧制相结合，高效短流程制备铝基碳化硼复合板材。主要研究：表面活化处理与合金成分对碳化硼活化性能和界面结合性能的影响；半固态剪切/搅拌作用下碳化硼颗粒分散机理及界面结合机理；剪切/振动作用对铝基碳化硼半固态浆料初生固相及浆料均匀性的影响；铝基碳化硼复合材料流变轧制成形过程中组织形成机理；为建立铝基碳化硼复合板材的短流程制备方法提供理论指导。

项目针对铝基碳化硼复合材料制备工艺复杂、流程长、碳化硼与铝基体界面润湿性差的突出问题，以及国家对高性能铝基碳化硼复合材料的需求，提出采用半固态复合与流变轧制相结合，高效短流程制备铝基碳化硼复合板材。.圆满完成了项目任务书中的研究计划，获得主要成果如下：（1）获得了表面活化处理与合金成分对B4C颗粒活化性能和界面结合性能的影响；（2）采用数值模拟揭示了半固态搅拌A356-B4C流体速度场分布规律；（3）揭示了剪切/搅拌作用下B4C颗粒分散机理及界面结合机理；（4）获得了流变轧制成形A356-B4C复合材料组织性能，优化了流变轧制成形工艺参数，制备了综合性能优良的铝基碳化硼复合板材；（5）获得了二次轧制对流变轧制复合板材微观组织及摩擦磨损性能的影响。发表标有资助号的论文15篇，SCI/EI收录14/10篇；获得授权国家发明专利2件；以第一完成人获日内瓦国际发明金奖、冶金科学技术二等奖；培养研究生毕业13名；参加国内外学术会议11次，担任大会副主席和分会主席3次，作邀请报告8次。.项目研究的科学意义与创新点如下：（1）采用表面活化处理提高了B4C颗粒的活化性能和界面结合性能；（2）采用数值模拟指导搅拌杆结构设计，通过半固态搅拌使B4C颗粒均匀分布；（3）分析了剪切/搅拌作用下B4C颗粒分散机理及界面结合机理；（4）采用流变轧制成形制备了组织性能优良的A356-B4C复合材料。