碳纤维增强B4C/Al多维异质材料中子吸收效应交互作用机制及热变形机理研究

B4C particles reinforcing Al matrix composite (B4C/Al) is the neutron absorber with optimum overall performance, however the high content B4C as hard particles can isolate Al matrix from each other, which makes B4C/Al difficult to prepare and machine. Based on the high strength and large neutron reflecting cross-section of carbon fibers(Cf), the item presents carbon fiber reinforcing high content B4C/Al neutron absorber called as Cf-HBAM, aming at improving the strength of the material as well as neutron absorbing capacity.. This item researches the mechanism and probability rule of both 10B neutron absorption and C neutron reflection, and the interaction mechanism of two effects by using of Monte Carlo method and MCNP software, designs the component system of neutron absorbing element, establishes the design model of Cf-HBAM. This item will prepare Cf-HBAM with structure / function integration, optimize the extrusion dies and process parameters of non-similar deformation process by thermal simulation test combined with Deform software, explore the coordination mechanism of plastic deformation among carbon fiber Cf, B4C particles and Al matrix, as well as some thermodynamics and kinetics problems research the mechanism of surface modification for both Cf and B4C, clarify the key basic problems about the heterogeneous bonding between the matrix and reinforcing phase, Explore the effect mechanisms of microscopic interface connection and grain refinement effect on the macroscopic thermal deformation behavior , which will improve the preparing and machining performances.. The research will enrich the scientific theory of nuclear structure / functional materials, which will be helpful to the independent research of spent fuel storage device, safe use and life evaluation.

B4C/Al材料是综合性能较优的中子吸收材料，但高含量B4C硬质颗粒隔离Al基体，使得其加工制备困难、服役性能降低。基于碳纤维强度高和中子反射截面大的双重优势，本申请提出了一种碳纤维Cf增强B4C/Al基新型中子吸收材料Cf-HBAM，旨在改善该类材料强韧度的同时，提高其中子吸收能力。.采用MCNP软件模拟计算乏燃料辐射能谱下10B吸收和C反射中子的几率规律，及两钟效应的交互作用机制，设计中子吸收元素组分体系。制备集结构/功能一体化的材料，采用热模拟试验结合Deform软件优化非相似变形过程中的工艺参数，探索碳纤维Cf、B4C颗粒与Al基体多维异质材料之间的协调塑性变形机制，热力学和动力学等关键基础问题，研究Cf和B4C表面改性机理和方法、与Al基体的异质材料界面接合机理，探究微观界面连接及细晶化效应对宏观热变形行为的影响机制。.研究成果将丰富核材料的科学理论，有利于乏燃料贮运装置自主研发

随着核电事业的飞速发展，对于乏燃料储存和运输过程中所使用的中子屏蔽材料引起了国内外学者的广泛关注。B4C/Al材料是综合性能较优的中子吸收材料，但高含量B4C硬质颗粒隔离Al基体，使得其加工制备困难、服役性能降低。本课题组基于碳纤维强度高和中子反射截面大的双重优势，设计出了均匀混合和层状Cf/B4C/Al中子屏蔽材料CFHBAM，旨在改善该类材料强韧度的同时，提高其中子吸收能力。.采用MCNP软件模拟计算乏燃料辐射能谱下10B吸收和C反射中子的几率规律。对均匀混合和层状Cf/B4C/Al中子吸收材料组份及配比进行了优化设计；通过粉末冶金法（真空热压烧结+热轧+热挤压）制备Cf/B4C/Al中子吸收材料；采用加弧辉光技术在Cf和B4C颗粒表面实现了Ti-Cu-Al表面合金化，合金层与碳纤维和颗粒之间的界面结合良好；利用SEM、TEM对材料微观组织结构进行分析，表明碳化硼颗粒、碳纤维及铝颗粒三维异质结构之间结合较好，界面缺陷较少，无气孔等，断口形貌显示有部分B4C颗粒和多数纤维被拉断，表明碳化硼颗粒和碳纤维与铝基体之间连接良好。均匀混合和层状Cf/B4C/Al材料拉伸试验结果表明：层状Cf/B4C/Al要比均匀混合Cf/B4C/Al材料具有更好的塑性变形能力。Cf/B4C/Al中子屏蔽材料应力曲线呈现三个典型变化阶段：材料屈服之前的高加工硬化率阶段、相对较低的硬化率阶段、高硬化率阶段。EBSD测试结果表明： B4C颗粒和Cf能够促进动态再结晶形核、抑制铝晶粒生长、降低铝晶粒的优先取向，在变形量增大的情况下，动态再结晶晶粒的含量增加。另外，课题组也研制了含稀土元素的Gd2O3/6061Al新型中子吸收材料。.研究成果将推进乏燃料储运中子吸收材料的国产化进程。