两类钒基合金的辐照硬化研究

钒合金(V-Cr-Ti系列)是重要的聚变堆结构候选材料,但是相比于铁素体/马氏体钢等其他候选材料,有关钒合金(V-Cr-Ti)的辐照损伤研究较为缺乏。利用载能离子束模拟聚变堆中子辐照条件,对V-4Cr-4Ti和V-5Cr-5Ti两种样品进行了载能He离子和重离子辐照实验。实验采用离子束梯度减能方法在样品中产生辐照损伤的坪区,利用纳米压痕技术测试材料的辐照硬化效应。结果表明,样品纳米硬度的深度递减现象可以用Nix-Gao模型很好描述,高能重离子辐照的样品中软基体效应可以有效避免;在He离子辐照情形,He浓度(以原子百万分率计(Atomic parts per million,APPM))/位移损伤(以每原子平均离位数计(Displacement per atom,DPA))大于4 200/0.2时,两种钒合金样品出现硬化饱和现象;相近位移损伤水平下,He与空位的结合导致缺陷集团的加速长大,致使材料的辐照硬化远大于重离子辐照情形。     

Manufacturing pressurized creep tubes from highly purified V-4Cr-4Ti alloys, NIFS-Heat2

A fabrication process for pressurized creep tubes (PCTs) for a highly purified V-4Cr-4Ti alloy, NIFS-heat2 was established. No increase in impurity contents in PCTs was detected during the tube manufacturing process. In a preliminary thermal creep test, homogeneous deformation was observed over entire tube length, which verifies reliability of creep measurement by using the present PCTs.     

The Influence of lithium environment on tensile behavior and microstructure of V-4Cr-4Ti

Thermal tests exposed V-4Cr-4Ti in static liquid lithium at 700 and 800 °C for 250, 500, and 1000 h. Post-exposure examination included chemical analysis of interstitial impurities in V-4Cr-4Ti to monitor impurity transfer, and tensile tests at room temperature and 500 °C. Microstructures were characterized by room-temperature electrical resistivity measurements and transmission electron microscopy. Oxygen was not depleted from V-4Cr-4Ti when nitrogen pickup occurred during lithium exposures. In spite of a significant increase in interstitial impurity concentration, the matrix interstitial solute content was reduced due to precipitation. Plate-shaped precipitates in the matrix and globular precipitates at grain boundaries were formed during lithium exposures at 700 °C, while only globular precipitates were observed at grain boundaries at 800 °C. Increases in strength, decreases in ductility, and reduced dynamic strain aging resulted. Ductility remained high after 1000 h exposures at both 700 and 800 °C.     

V-5Cr-5Ti合金中杂质元素氧、氮、氢的测定

采用脉冲红外吸收法、热导法和高频感应热导法分别测定了V-5Cr-5Ti合金试样中氧、氮和氢的含量。讨论了释放温度、电流、助熔剂、坩埚类型、空白值、试样量对测定结果的影响。结果表明:分析功率5.0kW,采用高温坩埚、镍做助熔剂进行测定,氧和氮的测定相对标准偏差分别为8.8%和12.4%(n=6),加标回收率分别为93%~112%和90%~110%。分析功率85%,采用石英坩埚、镍做助熔剂进行测定,氢的测定相对标准偏差优于3%(n=6),加标回收率为96%~104%。     

Stability and migration property of helium and self defects in vanadium and V-4Cr-4Ti alloy by first-principles

The stability and migration behavior of helium and self defects in vanadium and V-4Cr-4Ti alloy are studied by first-principles calculations. The tetrahedral site is found as the most stable configuration for interstitial He, followed by the octahedral and substitutional sites. Among the self defects, the monovacancy has lower formation energy (1.71 eV for V and 2.14 eV for V-4Cr-4Ti alloy) than the self interstitial ones. The migration energies for He hopping between the tetrahedral sites are 0.06 and 0.09 eV for vanadium and V-4Cr-4Ti alloy, respectively. Our calculations reveal strong repulsion between two interstitial He atoms and strong attraction between He and vacancy, suggesting that vacancy acts as a trapping site for He impurity and a seed for further bubble formation.     

The Effects of Al,Cr on the Oxidation Behavior of a V-4Ti Alloy

Oxidation experiment was performed in air at elevated temperature for three kinds of vanadium alloys. The features of the oxides and the role of the alloying elements were analyzed. All specimens exhibited a parabolic kinetic behavior of weight gain with the exposure time. The alloys can't be used in air at the temperature over 700℃, below which, V4Ti3Al showed a much lower oxidation rate than the V4Cr4Ti alloy. It was found that Al in the alloy was segregated to the specimen surface in the process, and formed into Al2O3 on the surface, hence decreasing the formation of V2O5. The oxides on the surface were nucleated in a small number density and grew to a large size, giving more protection to the matrix alloy.     

燃料元件Zr—4端塞与钽管的焊接技术研究及其应用

介绍了压水堆燃料元件包壳Ｚｒ－４端塞与用于引入钨铼热电偶的钽管间的焊接技术及其焊缝的水压试验和腐蚀试验，结果表明焊缝表面成型良好，无冶金缺陷，承压９．０ＭＰａ未发现泄漏，焊缝在４５０℃熔融ＰｂＢｉ合金中经１００ｈ处理后有腐蚀迹象，但经预生氧化膜处理后能减缓ＰｂＢｉ的浸浊，最后提出了辐照罐设计和装配有时应采取的措施。     

体细胞HPRT基因位点突变检测技术及其在电离辐射研究中的应用

次黄嘌呤磷酸核糖转移酶（HPRT）基因在单基因突变的研究中是一个经黄的基因位点。本文概述了HPRT基因位点突变检测的原理,列出了几种检测方法,并讨论了影响HPRT基因突变频率测定的几个因素以及HPRT基因突变在生物剂量估算中的应用,最后与其它辐射生物剂量计进行了比较。     

Development of Thin Film Thermometer and Its Application to Radiation Loss Measurement in JFT-2 Tokamak

A thin film thermometer with high sensitivity and small response time has been developed. A nickel film was deposited in a vacuum on a backing plate of stainless steel 0.05 mm thick. The pattern of nickel film was so designed to provide sufficient accuracy. A small heat flux of 0.5 W/cm² is measurable with a response time of less than 1 ms. The thermometer was applied to radiation loss measurement in JFT-2 tokamak. The power loss due to the radiation was found to be about 30% of the total power input.     

Measurement of the thermoluminescent response (supralinearity and efficiency) of LiF : Mg,Ti exposed to 0.7 MeV protons

The irradiation of LiF : Mg,Ti (TLD-100) chips by a defocused 0.7 MeV proton beam from an electrostatic accelerator has been achieved using radiochromic dye film to evaluate the beam transversal intensity distribution. The dose-response has been measured at fluences between 2.4 × 10⁸ and 5.7 × 10¹¹ p/cm² and peaks 3–9 show linear-supralinear-sublinear response. The efficiency, relative to ⁶⁰Co γ-rays, measured for the total thermoluminescent (TL) signal and peaks 5 and 7, equals 0.33, 0.22 and 1.4, respectively. The comparison of these and other low-energy data for peak 5 with Track Structure Theory (TST) efficiency calculations indicate that the latter must take into account the stopping of the incident ions in the dosimeter to achieve a reasonable agreement with the observations. In general, neither TST, nor Modified Track Structure Theory (MTST) are able to simultaneously predict the response to 5.3 MeV α-particles and 0.7 MeV protons for all the studied glow curve peaks. Track Interaction Model (TIM) and Unified Track/Defect Interaction Model. (UNIM) calculations of the supralinearity function f(D) of peaks 5 to 8 for 5.3 MeV α-particles and peaks 5 to 9 for 0.7 MeV protons, qualitatively describe the general trends measured in this work; only the UNIM agrees quantitatively with the data in both systems.     

一种基于混合传导模型的一回路结构材料腐蚀-活化-迁移模型及其应用

为了定量分析反应堆冷却剂加锌工艺对一回路系统堆芯外放射性水平的影响,本文结合描述材料微观腐蚀过程的混合传导模型(MCM)和描述腐蚀产物活化、迁移及沉积的宏观输运模型,形成了能够系统性描述一回路结构材料腐蚀-活化-迁移的联合模型,并通过遗传算法分析及文献调研确定模型各主要参数。经校验表明该模型能够有效计算正常运行工况下一回路中结构材料的均匀腐蚀程度,同时也能给出结构材料表面沉积层的放射性活度分布。使用该模型对加锌前后系统内不同分区的活度分别进行了计算,结果表明加锌工艺能显著降低一回路堆芯外放射性水平。