【作者】 张华锋； 郑剑平； 杨启法； 张征； 李鑫； 赵俊；

【Author】 ZHANG Hua-feng;ZHENG Jian-ping;YANG Qi-fa;ZHANG Zheng;LI Xin;ZHAO Jun;China Institute of Atomic Energy;

【机构】 中国原子能科学研究院；

【摘要】 难熔钼-铌合金单晶材料具有熔点高、高温力学性能优异和高温下不存在再结晶的优点以及一些多晶材料无可比拟的特殊性能而被广泛地用于高温部件。在能够实现直接热电转换的高温反应堆中,利用单晶材料制备的部件既用作核燃料的包壳,同时又实现高温热电转换。这些部件工作在高温和核燃料肿胀施加内压载荷的联合工况下,必然会发生高温内压蠕变。因此,钼-铌合金单晶材料的高温内压蠕变性能是决定部件寿命的关键因素。本文对两种铌含量分别是3wt%和6wt%的国产钼-铌合金单晶材料在高温下(0.65T_m)内压蠕变性能进行测试,并结合微观组织结构特点分析合金元素铌对蠕变性能的影响。内压载荷由充入薄壁管状样品内部的惰性气体来施加,周向应力是5~15MPa,最终得到两种材料的稳态蠕变速率分别是10~4~10~6/h和10~5~10~7/h,应力指数n分别是5.4和3.4。分析结果表明:1)随着铌含量的增加,钼-铌合金单晶材料的内压蠕变性能逐渐增强;2)随着铌含量的增加,基体中形成更多的亚晶,析出相由粒状变成杆状,使得钼原子的扩散减弱,从而提升了材料的高温强度。更多还原

【Abstract】 Refractory alloy single crystal materials can be served as high temperature components because they have high melting point,advanced mechanical properties and stabilized microstructure at elevated temperature,and some specific properties.They are wildly used as cladding materials in some special nuclear reactor.In this case,they are served under the conditions of high temperature and inner pressure load,so the inner pressure creep property is the key factor to the lifetime.In this paper,the inner pressure creep property and microstructure of two kinds of domestic Mo-Nb alloy single crystal at an elevated temperature（⁰.65T_m）was examined.The niobium concentration of the materials is 3wt%and 6wt%respectively.Biaxial load was applied on the tube specimen by the inert gas,the hoop stress is 5¹5MPa,The steady-state creep rate has been deduced out and is10^-410^-6/h and(10^-510^-7)/h respectively for the two kind of material in the range of the test stress.The stress exponent n is also determined as 5.4 and 3.4.The following conclusions are made according to the results of this paper:1)the inner pressure creep properties are enhanced by increasing the concentration of Nb;2)with the increasing of Nb concentration,more sub-grains were found in the matrix and the shape of precipitates was changed from particle to shaft,which make the diffusive of Mo reduced.更多还原