氘和氦离子辐照下CLAM钢的辐照硬化与微结构演变

Irradiation Hardening and Defects Distribution in CLAM Steel under Deuterium and Helium Ion Irradiation

结合先进电子显微术和纳米压痕分析,对低活化马氏体CLAM钢的辐照行为进行了研究。在室温下对CLAM钢进行了单一注D+、单一注He+以及先注D+后注He+三种方式的离子辐照。纳米压痕硬度结果显示,离子辐照后的CLAM钢均产生了明显的硬化。通过对纳米压痕硬度曲线的拟合,得到各离子辐照后的硬化率。结果表明,注D+的辐照硬化程度最低,而注He+与D+、He+共同辐照的硬化程度均很明显。微观结构分析表明,沿离子注入深度方向,辐照缺陷密度逐渐增加然后减少;在注入深度峰值附近,产生了数密度较多的缺陷。对于单独注入He+离子以及先注D+后注入He+的CLAM钢,都产生了大量细小弥散的He泡,并且由于离子协同效应后者出现深度较浅的泡;单独注入D+的CLAM钢,并没有出现泡。注He+样品中既有位错环也有He泡,硬化效应比只有位错环的注D+样品明显;而先注D+后注He+的样品,由于注D+产生的缺陷在后续注He+时会有一定的回复,硬化效果不是注D+和注He+的简单叠加,体现出协同效应。

The irradiation behavior of a China low activation martensitic（CLAM） steel was investigated by advanced transmission electron microscopy combined with nano- indentation measurement. The CLAM steel was irradiated by single-（D＋）, single-（He＋） and sequential-（D＋plus He＋subsequently） ions respectively at room temperature. The nano- indentation hardness results show that all of the irradiated specimens exhibited obvious hardening. The irradiation hardening rate was obtained for each specimens by fitting the experimental data using the modified NGK model, in which D＋implanted samples had the lowest radiation hardening level while the one for He＋injection and D＋＋ He＋implanted samples were significant. The microstructure analysis indicates that the defect density gradually increased first and then decreased along the implantation depth direction. High- density irradiation induced defects were present at the vicinity of the implantation peak depth. Homogeneously distributed fine bubbles were observed in both single-（He＋） and sequential-（D＋plus He＋subsequently） irradiated samples with the bubble appearance at shallower depth for the latter ones because of the synergistic effect. No bubbles were found in single-（D＋） irradiated samples. The hardening rate of He＋implanted samples, in which both dislocation loops and helium bubbles occurred, is greater than D＋implanted samples. In D＋＋He＋irradiated samples,certain defects occurred by D＋will recover when the samples are being irradiated by He＋. Therefore, the hardening rate of D＋＋He＋irradiated samples is not equivalent to the rate of D＋irradiated samples plus He＋irradiated samples. Irradiation hardening results from the synergistic reaction.