利用同步辐射散射和衍射研究金属中的氦脆问题

项目名称： 利用同步辐射散射和衍射研究金属中的氦脆问题

项目编号： No.11505273

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 谢若冰

作者单位： 中国科学院上海应用物理研究所

项目金额： 23万元

中文摘要： 出于能源发展的战略需求，我国正在研发钍基熔盐堆，以促进核电的应用。在熔盐堆中，镍基合金因为比较耐熔盐腐蚀，成为首选的结构材料。但是在反应堆的服役环境里，镍基合金因为受到中子辐照和裂变产物的影响，会有大量的氦进入金属内部，这些氦聚集形成氦泡，会造成材料的脆化，又称氦脆。所以研究不同的辐照条件下氦在金属里面的存在方式及其和宏观力学的联系是有很大的应用价值的。本项目的研究拟采用粒子加速器往金属镍里面注氦，然后通过同步辐射散射来获得氦泡的浓度、大小，微聚焦衍射来获得镍晶格的应力变化。通过分析这些微观结构变化的信息，再结合测量注氦后的镍的硬度、弹性模量等宏观力学性质的变化，来研究在辐照环境中，镍基金属的氦脆的形成条件和机制，从而进一步提出镍基合金改性的方向。

中文关键词： 同步辐射；小角散射；微聚焦衍射；氦脆；核能

英文摘要： As the energy demand rises worldwide, electricity coming from nuclear power plants has become a more environmentally friendly and economically viable substitute for fossil. China is developing Thorium fueled molten salt reactor. In molten salt reactor environment, nickel based alloy is the primary choice of structural material due to its corrosion resistance to the salt. However, because of alpha decay induced by neutron irradiation, helium will accumulate in the metal during its service in the reactor. These helium atoms can aggregate and form nanosized bubbles. Eventually the metal will become brittle as large amount of helium bubbles exist in it. This phenomenon is called helium embrittlement. So it is important to understand the existent form of helium atoms in nickel based alloy and its correlation with the mechanical properties. This research will induce helium into nickel via ion accelerator. In this way the energy and number of helium atoms are controllable. The size and concentration of helium bubbles can be obtained by synchrotron X-ray scattering. The deformation of the crystalline structure can be probed by micro-focus diffraction. The information about the change of the micro-structure of the metal, combined with the information about the change of the mechanical properties such as hardness and elastic module, can be used to study the mechanism of the formation of helium bubbles and how it affects the mechanical properties, and hence propose a possible direction to improve the nickel based alloy for its application in reactors.

英文关键词： synchrotron;SAXS;micro-focus XRD;helium embrittlement;nuclear energy