奥氏体不锈钢辐照肿胀和偏析的研究进展

Research Progress on Void Swelling and Radiation-induced Segregation of Austenitic Stainless Steel

随着社会对能源需求的增加,核能作为一种可大规模替代传统化石能源的清洁能源备受关注。目前我国正在大力推动第四代先进核反应堆技术的研发,这对反应堆结构材料的性能提出了更高的要求。由于反应堆堆芯的强烈辐照,作为堆芯结构材料的奥氏体不锈钢长期服役会发生辐照损伤现象,尤其是辐照肿胀和偏析,威胁反应堆运营安全。研究发现,奥氏体不锈钢的辐照肿胀和偏析现象与辐照剂量、辐照温度、合金元素成分等密切相关。对于辐照肿胀,常用冷加工和添加合金元素等方法进行控制,其中15-15Ti奥氏体不锈钢能够承受大于100 dpa的辐照剂量,被选为快堆候选包壳材料。但这两种方法开发的奥氏体不锈钢仍未达到先进核反应堆对奥氏体不锈钢抗辐照性能的要求,为此需要对控制所有辐照损伤效应的点缺陷的扩散行为进行更深入的系统和实验分析,以深入理解辐照肿胀现象。对于辐照偏析,其产生机制一直存在争议,主要有空位机制和间隙原子机制两种观点,但奥氏体不锈钢的辐照偏析很可能是这两种机制混合控制的结果,为此仍需进一步建立更优化的动力学模型进行研究。此外,近期研究表明辐照缺陷的一维迁移现象可能与辐照损伤密切相关,但仍存在一些细节需要进一步的实验研究。本文阐述了奥氏体不锈钢发生辐照肿胀和偏析的相关影响因素,分析了控制辐照肿胀的现有手段的不足,总结了辐照偏析发生机制的争议和相关进展,归纳了奥氏体不锈钢抗辐照性能研究存在的问题并对未来的研究方向进行了展望。

As society’s demand for energy increases,nuclear energy has become the focus of recent studies.China is strongly promoting the development of fourth generation nuclear reactor,which puts higher requirements on the performance of reactor structural materials.Austenitic stainless steel,as the core structure material,will undergo radiation damage under long-term service due to the intense radiation in the reactor core,especially the void swelling and radiation-induced segregation,which threaten the safety of the reactor operation.Void swelling and radiation-induced segregation of austenitic stainless steel are closely related to irradiation dose,irradiation temperature and alloy composition.Cold working and alloy elements are usually used to control void swelling.The 15-15Ti austenitic stainless steel shows potential for cladding of fast breeder reactor due to withstanding radiation doses over 100 dpa.However,the austenitic stainless steels developed by these two methods have not fully satisfied the requirement for service.Point defects govern the radiation damage effects;therefore,a more in-depth systematic and experimental analysis on the diffusion behavior of point defects is essential to understand the void swelling.Two controversial views were proposed on the mechanism of radiation-induced segregation,that is,vacancy mechanism and interstitial atomic mechanism.However,the radiation-induced segregation of austenitic stainless steel may be governed by both;subsequently,a more optimized kinetic model needs to be established for further study.In addition,recent studies show that the one dimension motion of radiation defects is related to radiation damage,but further research is essential to explore some experimental details.In the present paper,we review the influence factors of void swelling and radiation-induced segregation of austenitic stainless steel,the shortcomings of the existing controlling methods of void swelling,and the progress on the mechanism of radiation-induced segregation.Finally,we prospect the future research directions according to the existing problems of study on the anti-irradiation property of austenitic stainless steel.