B.X. Zhou
,
M.Y. Yao
,
Z.K. Li
,
X.M. Wang
,
J. Zhou
,
C.S. Long
,
Q. Liu
材料科学技术（英文）
In order to optimize the microstructure and composition of N18 zirconium alloy (Zr–1Sn–0.35Nb–0.35Fe–0.1Cr, in mass fraction, %), which was developed in China in 1990s, the effect of microstructure and composition variation on the corrosion resistance of the N18 alloy has been investigated. The autoclave corrosion tests were carried out in super heated steam at 400 °C/10.3 MPa, in deionized water or lithiated water with 0.01 mol/L LiOH at 360 °C/18.6 MPa. The exposure time lasted for 300–550 days according to the test temperature. The results show that the microstructure with a fine and uniform distribution of second phase particles (SPPs), and the decrease of Sn content from 1% (in mass fraction, the same as follows) to 0.8% are of benefit to improving the corrosion resistance; It is detrimental to the corrosion resistance if no Cr addition. The addition of Nb content with upper limit (0.35%) is beneficial to improving the corrosion resistance. The addition of Cu less than 0.1% shows no remarkable influence upon the corrosion resistance for N18 alloy. Comparing the corrosion resistance of the optimized N18 with other commercial zirconium alloys, such as Zircaloy-4, ZIRLO, E635 and E110, the former shows superior corrosion resistance in all autoclave testing conditions mentioned above. Although the data of the corrosion resistance as fuel cladding for high burn-up has not been obtained yet, it is believed that the optimized N18 alloy is promising for the candidate of fuel cladding materials as high burn-up fuel assemblies. Based on the theory that the microstructural evolution of oxide layer during corrosion process will affect the corrosion resistance of zirconium alloys, the improvement of corrosion resistance of the N18 alloy by obtaining the microstructure with nano-size and uniform distribution of SPPs, and by decreasing the content of Sn and maintaining the content of Cr is discussed.
关键词:
Zirconium alloys
,
null
,
null
,
null
Journal of Physics-Condensed Matter
Based on ab initio total energy calculations, Li, Na and Ag interstitials are found to be stable with at least a 1.56 eV energy barrier to transform to a zinc substitutional site in ZnO, whereas K interstitial has a relatively small energy barrier at 0.79 eV. The isolated dopant substitutional defects (LiZn, NaZn, KZn and AgZn) are found to be rather stable, with at least a 3.4 eV energy barrier to transform to an interstitial site. All of the dopant interstitials (Lii, Nai, Ki and Agi) are fast diffusers. The diffusion of Li interstitial is isotropic, whereas the diffusion of Na, K and Ag interstitials is highly anisotropic. Fundamental processes of the vacancy-assisted mechanisms are systematically investigated and specific values of the energy barriers are obtained.
关键词:
augmented-wave method
张立春
,
何安强
,
叶恒强
,
张永昌
材料研究学报
用HRTEM、TEM及EDAX分析研究了Al─Li—Cu—Mg—Zr合金中的一种新相(暂名H相)和六角Z相的结构,确定H相具有四方点阵,点阵参数为α=2.8nm,c=2.4nm,EDAX分析表明H相和Z相均含Al、Mg、Cu发现H相与Z相的共存取向关系为[100]‖[1120]Z,[1010]H‖[0001]Z。还观察到Z相中一种特有的旋转畴结构
关键词:
Al─Li─Cu─Mg─Zr合金.四方H相
,
tetragonal H phase
,
hexagonal Z phase
张立春
,
何安强
,
吴玉琨
,
叶恒强
,
张永昌
金属学报
利用高分辨电镜(HRTEM)和常规电子显微术研究了快速凝固Al-Li-Cu—Mg—Zr合金中Z相和T相的结构关系,发现两相间两种确定的晶体学取向关系,并以此为依据解释了Z相和T相的某些结构缺陷两相的结构有密切关联,其中一相中缺陷的扩展会导致另一相的形成
关键词:
Al-Li-Cu-Mg-Zr合金
,
Z hexagonal phase
,
T f.c.c. phase
,
shear structure
High Temperature Materials and Processes
In order to decrease the solubility of NiO cathode of molten carbonate fuel cell (MCFC) and develop materials and coatings for separators in the cathode side of MCFC, dysprosium was introduced to modify nickel. In present paper, binary Ni-Dy alloys containing 1, 3 and 5 mass%Dy respectively were prepared. The alloys are two-phase composed of a nickel solid solution and an intermetallic phase Ni17Dy2. The oxidation behavior of the alloys at 923-1023K in air was evaluated by thermogravimetric tests coupled with some physical analysis techniques. The samples pre-oxidized at 923K for 100h were then immersed in molten (0.62Li,0.38K)(2)CO3 at 923K to examine the effect of Dy on the lithiation of NiO in the melt. The results indicated that the addition of dysprosium to nickel increased its oxidation rate, except for Ni-1Dy at 1023K. The scales formed on the alloys were composed of NiO with a trace of DY2O3. The lithiation of NiO in molten (Li,K)(2)CO3 could be favored by the addition of dysprosium. For comparison, binary Ni-Y alloys were also examined. The effect of yttrium on the air oxidation and molten (Li,K)(2)CO3 corrosion of nickel was similar to dysprosium, except that the Y-containing precipitates in Ni-Y alloys underwent very fast preferential corrosion while the Dy-containing intermetallic phases in Ni-Dy alloys not.
关键词:
molten carbonate fuel cell;Ni-Dy alloys;oxidation;molten carbonates;lithiation;fe-20cr alloys;behavior;600-800-degrees-c;coatings
High Temperature Materials and Processes
The ternary carbonate eutectic mixture of Li(2)CO(3), K(2)CO(3) and Na(2)CO(3) as a heat transfer and storage medium has excellent thermophysical properties, but with high viscidity as compared with some other inorganic salts such as chlorides and nitrates. The addition of chlorides or fluorides to molten carbonates may improve their fluidity, but possibly making the melt become more corrosive. In this study, the corrosion behavior of type 304, 310 and 316 stainless steels in an eutectic (Li,Na,K)(2)CO(3) melt with and without an eutectic mixture of NaCl and KCl at 973K in air have been examined. The experimental results indicated that 310 steel shows a much better corrosion resistance in molten carbonates than both 304 and 316 steels, due to the formation of a continuous LiCrO(2) scale. The addition of chlorides to carbonates melt accelerated the corrosion of the steels, especially 310 steel, producing scales with more porosity.
关键词:
Stainless steels;(Li,Na,K)(2)CO(3);(Na,K)Cl;molten salts corrosion;latent-heat-storage;potassium carbonates;lithium;sodium
刘颖
腐蚀与防护
为了探讨在熔融碳酸盐中加入氯化物对不锈钢的腐蚀作用的影响,采用浸泡方法研究了304和310不锈钢在添加了氯化物的700℃熔融(Li,Na,K)2CO3中的腐蚀行为.结果表明,两种不锈钢都遭受了严重腐蚀,不锈钢的快速腐蚀与循环的氯化-氧化反应有关.
关键词:
不锈钢
,
(Li,Na,K)2CO3-(Na,K)Cl
,
熔盐腐蚀
,
氯化-氧化
胡标
,
尹明
,
王庆平
,
闵凡飞
,
杜勇
兵器材料科学与工程
基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究.通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热力学参数.V-Li、V-Na和V-K体系中的气相视为由组元V、Li、Li2、Na、Na2、K和K2混合的理想气体.与实验相图数据对比表明,获得的热力学参数能够准确地描述实验相平衡数据.
关键词:
V-M(M=Li,Na,K,Sc,Ag)
,
CALPHAD方法
,
相图
,
热力学模型
Radiation Effects and Defects in Solids
In this paper, we establish the high-order perturbation formulas of EPR zero-field splittings D, E and g factors, g(x), g(y) and g(z) for 3d(3) ions in a sort of rhombic symmetry where the symmetry axes and hence the crystal-field axes lie along the [001], [010] and [100] axes. From these formulas, the EPR parameters D, E, g(x), g(y) and g(z) for the rhombic Cr3+-V-M and Cr3+-Li+ defect centers in the tetragonal A(2)MF(4) (A = K, Rb, Cs; M = Mg, Zn, Cd) fluorides are calculated by considering the suitable defect-induced lattice distortions. The results are in reasonable agreement with the observed values.
关键词:
electron paramagnetic resonance;crystal-field theory;superposition;model;lattice distortions;Cr3+;A(2)MF(4) (A = K, Rb, Cs;M = Mg, Zn,;Cd;spin-orbit coupling;electron-paramagnetic-res;superposition model;cr-3+ centers;ions;rb2znf4;spectra;k2mgf4;k2znf4
