高能重离子辐照的低活化钢硬化效应  

Hardening of reduced activation ferritic/martensitic steels under the irradiation of high-energy heavy-ion

作　　者：丁兆楠 杨义涛[1] 宋银[1] 张丽卿[1] 缑洁[1] 张崇宏[1] 罗广南[2] 

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]中国科学院等离子体物理研究所,合肥230031

出　　处：《物理学报》2017年第11期54-62,共9页Acta Physica Sinica

基　　金：国家自然科学基金大科学装置联合基金(批准号:U1532262);国家磁约束核聚变能发展计划专项(批准号:2011GB108003)资助的课题~~

摘　　要：为了探讨聚变堆候选低活化钢的抗辐照性能,在兰州重离子加速器国家实验室HIRFL的材料辐照终端,利用63 MeV的^(14)N离子和336 MeV的^(56)Fe离子在-50?C下对一种国产低活化钢进行辐照实验.借助离子梯度减能装置,使入射离子能量在0.22—6.17 MeV/u之间变化,从而在样品表面至24μm深度范围内产生0.05—0.20 dpa的原子离位损伤坪区.利用纳米压痕仪测试样品辐照前后的显微硬度,通过连续刚度测量(constant stiffness measurement)得到低活化钢硬度的深度剖面信息.使用Nix-Gao模型很好地描述了纳米压痕硬度随深度递减的现象(压痕尺寸效应,indentation size effect),从而有效避免了低能离子辐照的软基体效应(softer substrate effect).正电子湮灭寿命谱显示低活化钢在辐照之后长寿命成分增加,说明样品中产生了大量缺陷形成空位团,从而导致了材料力学性能的变化,在离子辐照剂量增加至0.2 dpa时,平均寿命τ_m增加量逐渐变慢,材料中辐照产生的缺陷趋于饱和.In order to study the irradiation responses of reduced activation ferritic/martensitic （RAFM） steels which are candidates for fusion reactors, a reduced activation steel is irradiated at a terminal of HIRFL （heavy ion research facility in Lanzhou） with 63 MeV 14N ions and 336 MeV 56Fe ions at -50 ℃. The energies of the incident N/Fe ions are varied from 0.22 MeV/u to 6.17 MeV/u by using an energy degrader at the terminal, so that a plateau region of an atomic displacement damage （0.05-0.2 dpa） is obtained from the near surface to a depth of 24 μm in the specimens. Nanoindentation technique is used to investigate the nano-hardness changes of the samples before and after irradiation. The constant stiffness measurement is used to obtain the depth profile of hardness. The Nix-Gao model taking account of the indentation size effect （ISE） is used to fit the measured hardness and thus a hardness value excluding ISE is obtained. Consequently, the soft substrate effect for lower energy ion irradiation is effectively avoided. It is observed that there seems to be a power function relationship between the hardness and damage for the RAFM steel. The hardness initially increases significantly with the increase of irradiation damage, then increases slowly when the damage reaches to about 0.2 dpa. Positron annihilation is performed to investigate the defect evolution in the material. The positron annihilation lifetime spectra show that the long-lifetime proportion of the RAFM steel increases significantly after being irradiated. This means vacancy clusters are produced by the irradiation, resulting in the change of mechanics property. Even at low irradiation dose, point defects with high density are generated in the steel specimens, and subsequently aggregate into defect clusters, thereby suppressing the dislocation slip. The defect concentration in the material increases continuously with the increase of irradiation damage, which leads to the obvious irradiation hardening phenomenon. When the damage is high

关 键 词：低活化钢 N/Fe离子辐照 硬化 空位团 

分 类 号：TL627[核科学技术—核技术及应用]