12Cr-ODS钢中氧化物强化相（Y2O3）辐照损伤行为研究

本文采用电子束（e^－） 氦离子（He⁺）、氢离子（H⁺）束同时复合辐照方式研究12Cr-ODS铁素体钢中氧化物弥散强化相（Y₂O₃）辐照损伤行为,对不同辐照方式下辐照区内的氧化物形貌变化进行原位观察。研究结果表明,15dpa辐照后,氧化物周围出现微小高密度空洞,相界面变得不规则,氧化物在此特定条件下发生体积收缩或长大,尺寸有少量变化,但无明显溶解现象,对钢的性能不会产生影响。     

双束(He+/e-)辐照下氦对12Cr-ODS铁素体钢组织损伤影响研究

利用氦离子(He+)束和电子(e-)束双束同时辐照化学溶胶法制备的新型12Cr-ODS铁素体钢.实验结果表明,辐照初期,随着辐照剂量增加,点缺陷团(黑斑)在基体内形成,密度不断增大,尺寸长大缓慢,辐照剂量为0.8dpa时形成问隙型位错环.不同试验温度下,辐照均产生小尺寸高密度的空洞,随着辐照剂量增加,空洞尺寸长大缓慢,...     

双束同时辐照低活性Fe-Cr-Mn(W、V)合金微观组织损伤的影响

研究了时效热处理低活性Fe Cr Mn(W、V)钢双束同时辐照损伤行为 ,结果表明 :92 3K/ 3 0 0 0h时效合金 ,经单独电子辐照 (1 0a- 1)出现低密度空洞 ,而经双束同时辐照的时效合金 ,在辐照初期就形成间隙型位错环和微小空洞。与无时效合金相比 ,随时效温度增加 ,空洞尺寸、空洞密度和空洞肿胀量增大。随时效温度的提高碳化物析出数量增多 ,奥氏体中合金元素Cr、Mn、W、V降低 ,He的存在有效地促进空洞肿胀量增大。     

高温He离子辐照引起的Hastelloy N合金微结构变化研究

本文采用30 keV的He离子辐照Hastelloy N合金,辐照温度为500C,剂量分别为:1×10¹⁵、×10¹⁵、1×10¹⁶He⁺/cm²。利用扫描电子显微镜（SEM）研究了辐照后块体样品的表面形貌。结果表明,辐照后的块体样品均观察到了表面起泡现象。利用透射电子显微镜（TEM）研究了辐照后TEM样品微结构的变化。结果表明,低剂量(1×10¹⁵ He⁺/cm²)辐照的样品中出现了黑斑缺陷;随着辐照剂量的增加,开始出现位错环及纳米级的氦泡,同时黑斑密度减少;当剂量增至1×10¹⁶He⁺/cm²,位错环以及氦泡的尺寸和密度明显增大,晶界处氦泡更加密集。     

双束(H~+/e~-)同时辐照对12Cr-ODS钢氧化物稳定性影响

利用氢离子和电子双束(H~+/e~-)对用化学浸润法制备的新型12cr-ODS铁素体钢进行辐照,研究了辐照对12Cr-ODS钢氧化物稳定性的影响.对不同辐照剂量下原位观察辐照区内氧化物形貌的变化过程发现:辐照前和15 dpa辐照后,约10～20nm氧化物的尺寸并没有明显变化,而氧化物周围出现微小高密度空洞并没有影响氧化物的稳定性;当辐照温度升高至823 K时,大尺寸的氧化物Y_2O_3与基体的相界面变得不规则,但氧化物颗粒尺寸并不发生明显变化.实验结果表明:弥散强化相Y_2O_3尺寸稳定,无明显溶解现象.     

氨基羟基脲与Pu(Ⅳ)的还原动力学研究

研究了氨基羟基脲(HSC)与Pu(Ⅳ)的还原反应动力学,其动力学方程式为：-d_c（Pu(Ⅳ)）/d_t=kc（Pu(Ⅳ））c^1.06（HSC）c^-0.43（H⁺）c^-0.58（NO₃^-）,在22.1℃时反应速率常数k＝(11.8±1.1)（mol/L）^-0.046•s^-1,活化能为(71.0±1.0)kJ/mol。研究了氨基羟基脲浓度、H⁺浓度、硝酸根浓度、Fe³⁺浓度、UO₂²⁺浓度对氨基羟基脲与Pu(Ⅳ)还原反应速率的影响,增加氨基羟基脲浓度,降低H⁺浓度、硝酸根浓度,Pu(Ⅳ)还原速度增加;UO₂²⁺浓度和Fe³⁺浓度对Pu(Ⅳ)还原速度基本无影响。     

氨基羟基脲与HNO2氧化还原反应研究

研究了高氯酸介质中氨基羟基脲与HNO₂的还原反应动力学,其动力学方程式为－dc(HNO₂)/dt=kc(HNO2)c^0.25(HSC)c^0.42(H⁺),在1.0℃时反应速率常数k＝(1.05±0.05)(mol/L)^－0.67•s^-1,活化能为(73.1±3.0)kJ/mol。研究了氨基羟基脲浓度、H⁺浓度、硝酸根浓度对氨基羟基脲与HNO₂还原反应速率的影响。结果表明：增加氨基羟基脲浓度和H⁺浓度,HNO₂还原速度增加;高氯酸根浓度对氨基羟基脲还原HNO₂速率基本无影响。     

核石墨耐辐照性能的评价方法

在高温气冷堆运行过程中,作为堆内构件的石墨经受高温和快中子的辐照,会经历先收缩后膨胀的宏观尺寸形变,并在膨胀至原始尺寸时到达使用寿命。在石墨尺寸形变的过程中,石墨内部气孔的结构和数目均有明显变化。当辐照剂量接近使用寿命时,石墨内部气孔数目明显增加,导致其力学性能急剧下降而退出服役。He⁺、C⁺、Xe⁺离子辐照实验表明,在200keV10¹⁴cm^-2Xe⁺离子辐照下,石墨气孔形貌变化明显。这一结果可作为石墨辐照性能的评价方法。     

中子辐照导致线阵电荷耦合器件电荷转移效率退化实验研究

利用TRIGA型脉冲反应堆提供的快中子，对线阵电荷耦合器件进行中子辐照实验研究。研究结果表明：在10¹²～10¹³cm^-2中子注量范围内，该器件的电荷转移效率（CTE）随辐照中子注量的增加而线性下降；电荷转移效率的下降与电荷包在沟道中的转移时间及转移电荷包的电量有关。      

高温He离子辐照GH3535合金的损伤效应

采用500 keV的He离子在750 ℃下对GH3535合金样品进行辐照，然后利用掠入射X射线衍射（GIXRD）、透射电子显微镜（TEM）和纳米压痕仪分别对样品的氦泡和位错环辐照缺陷的演化及纳米硬度的变化进行了研究。结果表明，GH3535合金晶格辐照后发生了轻微畸变；离子辐照在样品中形成了大量尺寸为2～5 nm的氦泡和位错环。辐照产生的氦泡和位错环等缺陷在基体中钉扎位错，从而使材料产生了辐照硬化现象，样品硬度随辐照剂量的增加而增大。当辐照剂量达2×1016 cm-2时，辐照样品发生了明显的硬化饱和现象，利用Nix Gao模型计算得此时的硬化程度为64%。     

Investigation of the cause of peculiar irradiation behavior of 9Cr-ODS steel in BOR-60 irradiation tests

Four experimental fuel assemblies (EFAs) containing 9Cr-ODS steel cladding fuel pins were previously irradiated in the BOR-60 to demonstrate the in-reactor performance of 9Cr-ODS steel for use as fuel cladding tubes. One of the EFAs achieved the best data, a peak burn-up of 11.9at% and a neutron dose of 51 dpa, without any microstructure instability or any fuel pin rupture. On the other hand, in another EFA (peak burn-up, 10.5at%; peak neutron dose, 44 dpa), peculiar irradiation behaviors, such as microstructure instability and fuel pin rupture, occurred. Investigations of the cause of these peculiar irradiation behaviors were carried out. The detection sensitivity in an ultrasonic inspection test was shown to be low for the metallic Cr and metallic Fe inclusions. The peculiar microstructure change reappeared with high-temperature thermal-aging of the 9Cr-ODS steel containing metallic Cr inclusions. The strength and ductility of the defective part containing metallic Cr inclusions were appreciably lower than those of a standard part without the inclusions. The combined effects of matrix Cr heterogeneity (presence of metallic Cr inclusions) and high-temperature irradiation were concluded to be the main cause of the peculiar microstructure change in 9Cr-ODS steel cladding tubes in the BOR-60 irradiation tests. They contributed to the fuel pin rupture.     

硅对低活化马氏体钢电子辐照行为的影响

利用超高压透射电子显微镜研究了两种成分的低活化马氏体钢(CLAM钢)的辐照损伤行为。结果表明：电子辐照能在未添加硅的CLAM钢中产生辐照空洞;在450℃下辐照至14dpa时,空洞数密度约为8.7×10²¹m^－3,辐照肿胀率约为0.26％;在450℃下的辐照肿胀率明显比500℃下的高;当损伤率为2×10^－3dpa/s时,添加合金元素硅能显著提高CLAM钢的抗辐照肿胀能力,未在添加硅的CLAM钢中实验观察到辐照空洞的形成。在450℃下进行辐照时,添加硅的CLAM钢出现明显的辐照共格析出现象。     

注氘低活化马氏体钢在电子辐照下的缺陷行为

低活化铁素体/马氏体(RAFM)钢被视为国际热核聚变反应堆以及聚变反应堆的第1壁候选结构材料之一,很多国家均在研究不同的RAFM钢,中国低活化马氏体(CLAM)钢的研究亦正在进行。核聚变会产生氢、氦、氘及氚,这些气体元素与辐照缺陷结合在一起,对材料的辐照性能会产生较大影响。本文对注氘后不同温度下的辐照后微观结构进行研究。试验利用日本北海道大学的JEOL-1300高压电子显微镜研究注氘CLAM钢从室温到873K在1250keV电子辐照下的微观结构变化。研究结果表明,在电子辐照下,注氘产生的缺陷团会出现消失和长大两种现象,意味着间隙型与空位型位错环在注氘过程中同时产生。并研究了注氘产生的空洞。     

A SANS investigation of the irradiation-enhanced α–α′ phases separation in 7–12 Cr martensitic steels

Five reduced activation (RA) and four conventional martensitic steels, with chromium contents ranging from 7 to 12 wt%, were investigated by small angle neutron scattering (SANS) under magnetic field after neutron irradiation (0.7–2.9 dpa between 250 and 400 °C). It was shown that when the Cr content of the b.c.c. ferritic matrix is larger than a critical threshold value (∼7.2 at.% at 325 °C), the ferrite separates under neutron irradiation into two isomorphous phases, Fe-rich (α) and Cr-rich (α^′). The kinetics of phase separation are much faster than under thermal aging. The quantity of precipitated α^′ phase increases with the Cr content, the irradiation dose, and as the irradiation temperature is reduced. The influence of Ta and W added to the RA steels seems negligible. Cold-work pre-treatment increases slightly the coarsening of irradiation-induced precipitates in the 9Cr–1Mo (EM10) steel. In the case of the low Cr content F82H steel irradiated 2.9 dpa at 325 °C, where α^′ phase does not form, a small irradiation-induced SANS intensity is detected, which is probably due to point defect clusters. The α^′ precipitates contribute significantly to the irradiation-induced hardening of 9–12 wt% Cr content steels.     

The influence of He/dpa ratio and displacement rate on microstructural evolution: a comparison of theory and experiment

A kinetic model was developed to investigate the influence of the displacement rate and helium generation rate on microstructural evolution in austenitic stainless steels. The model integrates the rate equations describing the evolution of point defects, small point defect clusters, helium-vacancy clusters, and the larger cavity size distribution that is responsible for observable swelling. Cavity (bubble) nucleation is accounted for by the helium-vacancy cluster evolution, while void formation occurs when bubbles grow beyond a critical size in the larger cavity distribution.

A series of ion irradiation experiments were used to both calibrate the model and to provide a comparison between model predictions and experimental observations. The experiments involved single and dual-beam irradiations of solution annealed AISI-316 stainless steel at 873 K. The displacement rates were in the range of 2 × 10⁻³ to 1 × 10⁻² dpa/s and the helium-to-dpa ratios were in the range of 0 to 50 appm He/dpa. The maximum displacement dose was 25 dpa. The experiments revealed a significant effect of helium on both the dislocation structure and the cavity distribution. The model predictions of helium effects over a broad range of He/dpa ratios and displacement rates were consistent with experimental observations.     

Effects of dose rate change under irradiation on hardening and microstructural evolution in A533B steel

Iron-ion irradiations were carried out for 0.09wt%Cu A533B steel specimens at 290°C to investigate effects of dose rate change during irradiation; the irradiations consisted of the base irradiation (with an unchanged dose rate) and an additional one with changed dose rates from 1 to 50 times that of the base one. Nano-indentation hardness measurements showed that the increase in hardness was higher for lower dose rate of the base irradiation. A similar trend was identified during the additional irradiation. Transmission electron microscope (TEM) and three-dimensional atom probe (3DAP) analyses were carried out for the quantitative characterization of defect features. Mn/Ni/Si/Cu-enriched clusters and dislocation loops were observed in all specimens. The increase in hardness mainly depended on the formation of the solute atom clusters. The square root of the volume fraction of the solute atom clusters provided a good correlation with the increase in hardness. The effects of dose rate and dose rate change during irradiation were explained by the formation of solute atom clusters.     

Understanding silicon-rich phase precipitation under irradiation in austenitic stainless steels

Atom probe samples have been Fe⁺ ion irradiated at different doses (from 0.5 to 10 dpa) and different temperatures (between 300 and 400 °C) in order to understand the mechanism of formation, under irradiation, of Si-rich phases in austenitic stainless steels. Atom probe results show the presence of Si-enriched clusters which can also be enriched in Ni and depleted in Cr. Number densities of solute clusters can be linked to number densities of dislocation loops already observed by transmission electron microscopy in a previous work. This suggests that solute clusters are formed by heterogeneous precipitation on dislocation loops. Furthermore, the evolution of the composition of solute clusters as a function of the irradiation temperature is consistent with a radiation-induced mechanism. Results are also compared with previous results obtained after neutron irradiation at lower dose rate (in term of dpa s⁻¹). The comparison is, here again, consistent with the radiation-induced mechanism. Thus, Si-rich clusters may be formed by radiation-induced segregation to dislocation loops. Results also show that Si is probably dragged to sinks via the interstitial mechanism.