“夹心饼干”式弥散型复合燃料板的断裂机理

Fracture mechanisms of sandwiched dispersion fuels

U3Si2 - Al弥散型复合燃料板元件是新发展的一种低浓化的研究堆燃料。该元件制备工艺复杂 ,使用环境特殊 ,加工环节对燃料板力学性能影响较大。而燃料板的力学性能优劣则是保证研究堆可靠使用的必要条件。因此 ,对研究堆使用的 U3Si2 - Al弥散型复合燃料板元件 ,通过扫描电镜对试件的拉伸断裂断口形貌、断口中芯体与包壳分布进行了分析与检测 ,并且讨论了燃料板的拉伸强度与断口间存在的关系 ,得到了燃料板断裂机理为芯体脆断导致包壳快速失效 ,拉伸断裂的决定因素是芯体的断裂延伸率 ,含 U3Si2 - Al弥散型复合燃料板比非退火态的铸铝延伸率要低。

U 3Si 2-Al is a recently developed dispersion fuel used in research reactors with a complicated production process that requires a special production environment. The mechanical properties of U 3Si 2-Al, which depend to a considerable extent upon the production conditions, are of great significance for the reliability and performance of the reactors. The microstructure morphology of the fracture surfaces of fuel plates under tension was investigated using the SEM technique. The structural features of the pellets and the claddings were analyzed to relate the tensile strength and the configuration of the fuel plate fracture surfaces. Fuel failure was found to be associated with brittle fracture of the pellet core, which leads to plastic collapse of the cores was a predominate parameter in the load-bearing capacity of the fuels plates. The elongation ratio of U 3Si 2-Al is less than that of unannealed cast aluminum.