贮氢合金吸氢致应力的实验研究和数学推导

贮氢合金已被广泛用作氚的贮存和增压材料，在吸放氢过程中发生晶格的膨胀和收缩，其非均匀形变对结构容器(贮氢床)的器壁产生应力，材料粉化导致自压实，形成应力集中。采用电阻应变测量法研究了贮氢合金吸放氢循环床体壁应力与循环次数、贮氢容量、壁厚以及装料分额的关系，并从理论上推导了壁应力与贮量的关系。     

贮氢材料在氚技术中的应用

简要介绍了在氚技术中应用贮氢材料的意义和在氚技术中应用的贮氢材料的研究现状、典型贮氢材料的特性、贮氢材料用于氚技术的优点，及贮氢材料在工业规模的氚处理技术中的应用情况。     

纳米AlNi金属间化合物的结构及其吸放氢行为

采用自悬浮定向流法制备AlNi纳米微粉。应用TEM、XRD和元素化学分析等检测手段对微粒材料的显微结构、相组成和成分构成进行了表征。结果表明,所制备的纳米颗粒为单相的AlNi,TEM形貌呈较规则的多边形,粒径分布范围为10～40nm。氢吸附实验表明：在3.43MPa氢压下,AlNi纳米微粉在90～100℃时有一释放氢过程,200℃时达到最大吸氢量,约为7.3%。     

45 LaNi5-xAlxDy（x=0.1，0.3，0.45，0.5）微观结构中子衍射研究

LaNi5贮氢合金由荷兰Philips公司于1969年首先研制出来，具有吸氢量大、易活化、不易中毒、平衡压力适中、吸放氢快、滞后小等优点。然而由于贮氢材料所固有的热力学性质，使其应用受到了一定限制。为满足各方面的需要，LaNi5贮氢合金从二元向多元化方向发展。人们首先考虑用不同的金属元素M取代部分Ni形成LaNi5-xMx（M为Al、Ti、Co等），其中以LaNi50xAlx最受关注。用Al部分替代合金中的Ni，可改进材料贮氢的稳定性，降低室温平衡离解压等。La—Ni—Al合金是聚变能开发中一种重要的贮氢材料；含有高浓度氢的La-Ni—Al合金还是新型无污染电池的候选材料之一，在国防工业和民用上有重要的应用价值。     

ZrV2金属间化合物的制备与物相分析

经电弧熔炼数次，在优化的热处理条件下均匀化，制备出ZrV2合金样品。利用Cerius2.0软件对C15型Laves相ZrV2金属间化合物的X射线衍射（XRD）谱的模拟结果和ASTM卡片，对所合成的样品进行物相分析。结果表明：未经热处理的样品，物相组成复杂；在优化的热处理条件下均匀化后的样品为纯化合物相的ZrV2合金，不含固溶体相。     

Nb-1Zr与316L不锈钢爆炸焊高温退火扩散层的显微组织分析

研究了Nb-1Zr合金与316L不锈钢爆炸焊在1 300 ℃退火后形成的互扩散层.该互扩散层宽度约为80 μm.用透射电子显微镜(TEM)分析观测到该扩散层中有大量针状析出相产生.经选区电子衍射(SADP)技术测定,析出相为亚稳定的ζ-(Nb, Ni)相,基体相为(Ni,Cr,Nb,C)Fe-α合金.     

66 贮氢合金正电子湮没和扰动角关联研究

本工作用正电子湮没和扰动角关联方法研究Pd0.75Ag0.25和LaNi4．25Al0.75两种贮氢合金。     

0Nb-lZr与304不锈钢电子束熔钎焊界面微观组织研究

利用光学显微镜、扫描电镜(SEM)和电子衍射能谱仪(EDS)分析了Nb-lZr合金与304不锈钢电子束熔钎焊接头的反应相种类和界面结构.研究结果表明,接头界面生成了ε-( Fe2Nb)和σ-(FeCr)两种反应相,形成了两个反应层.反应层Ⅰ是Fez Nb的疏松组织,反应层Ⅱ是Fe2 Nb与FeCr的双相片层柱状晶组织.反应层Ⅰ是接头脆化、产生裂纹的主要原因.接头的强度与扩散层厚度有关,当扩散层厚度为22μm时,接头试样的强度达到355 MPa的最大值.     

La—Ni—Al系贮氢材料的吸,放氢行为研究

研究了Ｌａ－Ｎｉ－Ａｌ系贮氢材料的吸、放氢行为。给出了ＬａＮｉ５－ｘＡｌｘ（ｘ＝０．２５、０．５０、０．７５、１．００）的吸附等温线、吸附速率及其氢化物的解吸平衡压与温度的关系曲线；定量确定了合金的吸附平衡压和饱和吸附容量等吸氢性能参数及基本的热力学参数ΔＨ㈠值和ΔＳ㈠值；初步探讨了上述参数与Ａｌ含量之间的定性关系。这为Ｌａ－Ｎｉ－Ａｌ系贮氢材料的应用提供了理论依据     

Zr3V3O金属间化合物的制备与物相分析

在惰性气体保护下，经电弧熔炼数次，制备出母相为Zr3V3O的合金样品。利用Material Studio软件建立了Ti2Ni型η相的Zr3V3O金属间化合物的晶体模型，依据ASTM卡片，对所合成的样品及其氘化物进行了物相分析。结果表明：熔炼所得的铸锭和非饱和氘化的样品物相组成复杂，主相为Zr3V3O金属间化合物相。     

Experimental investigation of the Zr corner of the ternary Zr-Nb-Fe phase diagram

Intermediate phases in the Zr-rich region of the Zr-Nb-Fe system have been investigated by X-ray diffraction, optical and electron microscopy and electron microprobe analysis. The chemical composition ranges covered by the alloys studied here are: (41-97) at.% Zr, (32-0.9) at.% Nb and (0.6-38) at.% Fe. The phases found in this region were: the solid solutions α-Zr and β-Zr, the intermetallic Zr₃Fe with less than 0.2 at.% Nb in solution, two new ternary intermetallic compounds (Zr+Nb)₂Fe `λ<sub>1</sub>' with a cubic Ti<sub>2</sub>Ni-type structure in the composition range (2.4-13) at.% Nb and (31-33) at.% Fe, and (Fe+Nb)<sub>2</sub>Zr `λ₂' indexed as hexagonal Laves phase MgZn₂ type (C14) with a wide range of compositions close to (35-37) at.% Zr, (12-31) at.% Nb and (32-53) at.% Fe.     

Identification and quantification of hydride phases in Zircaloy-4 cladding using synchrotron X-ray diffraction

Zirconium hydrides precipitate in fuel cladding alloys as a result of hydrogen uptake from the high-temperature corrosion environment of light water reactors. Synchrotron X-ray diffraction was performed at room temperature on stress-relieved Zircaloy-4 cladding with two distributions of hydrides - (1) uniformly distributed hydrides across the entire cladding wall and (2) hydride rim next to the outer surface. The δ-hydride phase was found to be the predominant hydride phase to precipitate for hydrogen contents up to 1250 weight parts per million (wt ppm). At a higher content, about 3000 wt ppm, although δ-hydride is still the majority phase, a significant amount of γ-hydride is also observed. At even higher hydrogen contents, in excess of approximately 6000 wt ppm, such as can occur in a highly dense hydride layer, peaks associated with the ε-hydride phase are also observed in the diffraction pattern. The volume fraction of hydrides was estimated as a function of hydrogen content using the integrated intensities of select diffraction peaks corresponding to the α-Zr matrix and the hydride phases. These estimated values agree well with calculated values from the independently measured concentrations. The results of this study indicate that hydride precipitation in Zircaloy-4 is a complex process of evolving hydride phases with increasing local hydrogen content.     

钛吸氕、氘和氚的热力学同位素效应

在金属氢化物热力学及动力学测试系统上测定了钛吸收氕、氘和氚单质气体的压力-组成等温线(p-c-T曲线),并根据范德荷夫方程得到了钛吸收氕、氘和氚形成不同物相时的热力学参数△H^0和△S^0。实验证明,钛吸收氕、氘和氚单质气体时有显著的热力学同位素效应,在相同温度、相同原子比下,吸气平衡压力从低到高依次是氕、氘和氚,但其反应焓变和熵变从小到大依次是氚、氘和氕。     

The growth of oxide and oxygen-stabilized alpha layers in steam-oxidized zircaloy

Experimental investigations of the oxidation of Zircaloy in steam at high temperatures suggest temperature gradients exist across the oxide and oxygen-stabilized α layers even when specimens are exposed under nominally isothermal conditions. This paper presents a simple model that permits one to calculate the ratio of the thickness, of the oxide to oxygen-stabilized α layers in the presence of temperature gradients as well as under truly isothermal exposure conditions. The shape of the oxide to oxygen-stabilized α thickness ratio curve as a function of temperature was found to be in excellent agreement with oxidation kinetics data that were used to derive a scaling factor for the model. Variations in the temperature dependence of this ratio from independent measurements can be reproduced if it is assumed that temperature differences on the order of 10°C exist between the oxide layer and the oxygen-stabilized α layer. Metallographic evidence is presented that suggests the rate-controlling oxidation step occurs in the vicinity of the interface between the oxide and oxygen-stabilized a layers     

Estimate of the Efficiency of Hydrogen–Metal Hydride (Intermetallic Compound) Systems in the Separation of the Three-Isotope Mixtures H–D–T

A method is developed for calculating apparatus for separating a three-isotope mixture H–D–T by the sorption method using hydrides of metals or intermetallic compounds. Relations are established between the partition coefficients and mass-transfer characteristics, determined for binary isotopic mixtures of hydrogen, and the parameters determining the isotopic equilibrium and the kinetics of mass transfer in the system gas–solid hydride phase with three isotopes. The efficiencies of various sorbents for deprotization of deuterium–tritium mixture are compared. 4 figures, 2 tables, 7 references.     

Hydriding properties of uranium alloys for purposes of searching for new hydrogen storage materials

Hydriding properties of uranium alloys have been studied to search for new hydrogen storage materials to be applied to hydrogen energy systems. Application of uranium-base hydrogen storage materials can be expected to alleviate the risk, as well as to reduce the cost incurred by globally-stored large amounts of depleted uranium left after uranium enrichment. Various uranium alloys have been examined in terms of hydrogen absorptiondesorption properties, among which UNi Al intermetallic compound showed promising characteristics, such as lower absorption-desorption temperatures and better anti-powdering strength. First principle calculation has been carried out on UNi Al hydride to predict the change of crystal structure and the lattice constant with increasing hydrogen content, which showed this calculation to be promising in predicting candidates for good hydrogen absorbers.     

Role of Intermetallic Precipitates in Hydrogen Uptake of Zircaloy-2

The hydrogen uptake behavior of two types of Zircaloy-2 specimens containing either fine intermetallic precipitates or coarse ones was studied at 623–723 Kin the pre-transition period of oxidation to clarify the role of the precipitates in the hydrogen transport through the oxide film. In the former case, the amount of hydrogen taken up was small and did not show the oxidation temperature dependence. In the latter case, the amount of hydrogen taken up was large and dependent markedly upon the oxidation temperature; it increased with decreasing oxidation temperature. These results were successfully explained with the model that the intermetallic precipitates remaining in a metallic state in the oxide film act as the fast transport route of hydrogen.     

Hydrogenation of zirconium film by implantation of hydrogen ions

In order to understand the dnve-in target in a D-D type neutron generator,it is essential to study the mechanism of the interaction between hydrogen ion beams and the hydrogenabsorbing metal film.The present research concerns the nucleation of hydride within zirconium film implanted with hydrogen ions.Doses of 30 keV hydrogen ions ranging from 4.30×10~(17) to1.43×10~(18) ions cm~(-2) were loaded into the zirconium film through the ion beam implantation technique.Features of the surface morphology and transformation of phase structures were investigated with scanning electron microscopy,atomic force microscopy and x-ray diffraction.Confirmation of the formation of 5 phase zirconium hydride in the implanted samples was first made by x-ray diffraction,and the different stages in the gradual nucleation and growth of zirconium hydride were then observed by atomic force microscope and scanning electron microscopy.     

Comment on ‘The first step for delayed hydride cracking in zirconium alloys’ by G.A. McRae et al., J. Nucl. Mater. 396 (2010) 130-143

The aim of this paper is a reply to McRae et al.’s paper entitled “The first step for delayed hydride cracking (DHC) in zirconium alloys” claiming that the first step of DHC is hydrogen diffusion, not nucleation of hydrides as demonstrated by Kim’s new model. Despite the authors’ claim that the crack tip concentration is higher than the bulk concentration due to the stress gradient, their claim violates the thermodynamic principle that the stressed region should have a lower potential of hydrogen or lower hydrogen solubility than the unstressed region. Furthermore, it is demonstrated that the Diffusion First Model (DFM) proposed by the author is defective in terms of kinetics because hydrogen diffusion before hydride nucleation just governs the rate of hydride nucleation, neither the rate of hydride growth nor the crack growth rate (CGR).