多尺度结构功能一体化中子吸收材料的制备与高温强化机制研究

Dry storage of spent nuclear fuel, as a new developing direction, has an urgent requirement for the materials having both neutron absorbing ability and good high-temperature mechanical properties. However, in our country, research and development on such neutron absorber materials with structural and functional performances are lacking. The composition design, fabrication route, microstructural characterization and high-temperature strengthening mechanism for these materials have not been systematically investigated yet. In this project, the composites reinforced by both micrometric B4C and nano-sized Al2O3 will be fabricated using powder metallurgy technique. The nano-sized Al2O3 particles will be exteriorly introduced by high-energy ball-milling and in–situ formed by self-oxidation of flake Al powders, respectively. The composite planks will be produced by hot-pressing and hot-extrusion, and the effects of the addition modes of nano-sized Al2O3 and the hot-pressing and hot-extrusion parameters on the microstructures and mechanical properties of the resultant composites will be studied. The characteristics of nano-sized Al2O3 particles and the fine microstructures at the B4C/Al and Al2O3/Alinterfaces will be examined by means of.TEM technique, etc. The high-temperature mechanical properties of the composites will be tested and the interaction mechanisms between nano-sized Al2O3 and Al grain boundaries/dislocations/micrometric B4C particles will be analyzed. These studies will contribute to elucidating the high-temperature strengthening mechanism of multi-scale particles, and therefore provide theoretical foundation and technical support for the composition design and the fabrication and processing parameter optimization of high temperature resistant neutron absorber materials.

作为乏燃料贮存发展的一个新方向，干式贮存对兼具中子吸收与高温力学性能的核用材料提出了迫切需求。然而，我国对这种结构功能一体化中子吸收材料的研发基本处于空白，对其成分设计、制备工艺路线、微观组织表征及高温强化机理尚未开展系统研究。本项目拟采用粉末冶金技术制备微米B4C与纳米Al2O3多尺寸增强铝基中子吸收材料。分别通过高能球磨外加法及片状铝粉自氧化法引入纳米Al2O3，采用热压结合热挤压制备复合材料厚板，研究纳米Al2O3引入方式及热压、挤压工艺对复合材料组织与性能的影响；采用TEM等技术手段分析Al2O3的特性以及B4C/Al和Al2O3/Al界面的精细结构；对复合材料进行高温力学性能测试，研究热力耦合条件下纳米Al2O3与Al基体晶界、位错及微米B4C的作用机制。通过这些研究，阐明多尺度粒子的高温强化机制，为新型耐高温中子吸收材料的成分设计、制备与加工工艺优化提供理论依据。

作为乏燃料贮存发展的一个新方向，干式贮存对兼具中子吸收与高温力学性能的核用材料提出了迫切需求。然而，我国对这种结构功能一体化中子吸收材料的研发基本处于空白，对其成分设计、制备工艺路线、微观组织表征及高温强化机理尚未开展系统研究。本项目采用粉末冶金技术制备微米B4C与纳米Al2O3多尺寸增强铝基中子吸收材料。分别通过高能球磨外加法及片状铝粉自氧化法引入纳米Al2O3，采用热压结合热挤压制备复合材料厚板，研究纳米Al2O3引入方式及热压、挤压工艺对复合材料组织与性能的影响；采用TEM等技术手段分析Al2O3的特性以及B4C/Al和Al2O3/Al界面的精细结构；对复合材料进行高温力学性能测试，研究热力耦合条件下纳米Al2O3与Al基体晶界、位错及微米B4C的作用机制。通过这些研究，阐明了多尺度粒子的高温强化机制，为新型耐高温中子吸收材料的成分设计、制备与加工工艺优化提供理论依据。