Hydrogen solubility and diffusion studies of Zr-based AB2 alloys and sol–gel encapsulated AB2 alloy particles

Hydrogen solubility and hydrogen diffusion coefficients have been studied in Ti_0.1Zr_0.9(Mn_0.9V_0.1)_1.1Fe_0.5Ni_0.5, Ti_0.1Zr_0.9Mn_0.9V_0.1Fe_0.55Ni_0.55 and (Ti_0.1Zr_0.9)_1.1Mn_0.9V_0.1Fe_0.5Co_0.5 in the temperature range 450–650 °C with hydrogen gas pressure up to 100 mbar and hydrogen concentration up to 0.03 hydrogen atoms per formula unit. H₂ absorption is exothermic, and the values of partial enthalpy of solution per H atom are in the range from −370 ± 10 meV to −466 ± 50 meV. The silica embedded AB₂ alloy particles have been prepared by sol–gel technique. P–C isotherms of encapsulated AB₂ alloy particles have been obtained in the pressure and temperature ranges 0–30 bar and 30–100 °C, respectively. Diffusion of H interstitials in sol–gel encapsulated Ti_0.1Zr_0.9Mn_0.9V_0.1Fe_0.5Ni_0.5, (Ti_0.1Zr_0.9)_1.1Mn_0.9V_0.1Fe_0.5Ni_0.5 and (Ti_0.1Zr_0.9)_1.1Mn_0.9V_0.1Fe_0.5Co_0.5 alloy particles have been studied between 500 and 650 °C with H₂ gas pressure up to 100 mbar and H concentration up to 0.014 H atoms per formula unit. Diffusion coefficient (D) of H interstitials has been determined for all these samples from the kinetics of hydrogen absorption. The activation energies have been calculated from temperature dependence of diffusion coefficient and the values are in the range 416 ± 15–897 ± 50 meV.     

Design of Zr-based AB_2 type hydrogen storage alloys

1　INTRODUCTIONPresently ,therearetwokindsofhydrogenstor agealloys (AB5andAB2 )usedinnickel metalhy dride (Ni/MH)battery .AB2 typehydrogenstoragealloyhasworseactivationperformanceandlowerini tialcapacitythoughitscapacityishigherandlifeislongerthanAB5alloy .Atthesametime ,AB2 typehydrogenstoragealloyismoreexpensivethanAB5typehydrogenstoragealloy .AlltheaboveaspectsembarrasstheactualapplicationofAB2 typehydrogenstoragealloy .PropertiesofAB2 typehydrogenstor agealloy ,suchascapacity ,…     

Phase-separated microstructures and shear-banding behavior in a designed Zr-based glass-forming alloy

We have employed a thermodynamic-computation approach to identify the composition of the Zr–Cu–Ni–Al alloy system exhibiting a two-liquid miscibility phase equilibrium in the liquid-temperature region, which tends to favor the occurrence of the liquid-phase separation. Guided by these calculated diagrams, a Zr-based alloy with a 10 at.% Al is designed, and its bulk-metallic glass (BMG) is prepared successfully by the copper-mould suction casting. A heterogeneous microstructure characterized by the existence of phase-separated regions with several to decades micrometers in size forms in the BMG. Under uniaxial compressive loading, the designed Zr-based BMG demonstrates the continuous “work hardening” and remarkable macroscopic plastic strain at room temperature. The improvement of mechanical properties is attributed to the unique glassy structure correlated with both the heterogeneous microstructure and the micro-scaled phase separation, leading to the extensive shear-band formation, interaction, and multiplication.     

Relationship between cooling rate and electrochemical performance of melt-spun AB_5 alloy

1　INTRODUCTIONNi/MHsecondarybatterieshaverapidlybeendevelopedandgraduallysubstitutedforNi/Cdbatter iesintherecentdecadeduetoitshighspecificenergydensityandhavingnopoisonouselementcadmium .TheactivematerialofnegativeelectrodewidelyusedinNi/MHsecondarybatteriesisAB5 typehydrogenstoragealloynowadays .However ,itisstillneededtoimprovethecomprehensive propertiesofAB5 typehydrogenstoragealloyforprolongingtheservicelifeofNi/MHbatteries .Anormalmethodtoimprovethecomprehensivepropertiesofthe…     

添加Si对A_2B_7型电极合金结构及电化学贮氢性能的影响(英文)

为改善La–Mg–Ni系A2B7型合金的电化学贮氢性能,在合金中添加一定量的Si元素,通过真空熔炼及退火处理的方法制备La0.8Mg0.2Ni3.3Co0.2Six(x=0-0.2)电极合金。研究Si元素的添加对合金结构及电化学贮氢性能的影响。结果表明,铸态及退火态合金均为多相结构,分别为Ce2Ni7型的(La,Mg)2Ni7相和CaCu5型的LaNi5相以及少量的残余相LaNi3。Si元素的添加没有改变合金的主相,但使得合金中的(La,Mg)2Ni7相减少而LaNi5相增加。添加Si显著地影响了合金的电化学性能。随着Si含量的增加,铸态及退火态合金的放电容量逐步降低,但循环稳定性却随着Si含量的增加而增强。此外,合金电极的高倍率放电性能、极限电流密度、氢扩散系数以及电化学交流阻抗谱的测试均表明合金的电化学动力学性能随着Si含量的增加先增加而后减小。     

Thermal degradation behavior of inconel 617 alloy

Inconel 617 alloy is a candidate material for potential use as an intermediate heat exchanger (IHX) and as a hot gas duct (HGD) in high-temperature gas-cooled reactors (HTGRs) for H₂ production. This alloy supports severe operating conditions of a pressure over 8 MPa and temperature that exceed 950 °C in He gas with some impurities. In this work, the oxidation behavior of Inconel 617 alloy was studied after exposure at 1050 °C for 2000 h in both air and He atmospheres. The external oxide scale was mainly composed of Cr₂O₃ and small amount of TiO₂. The internal oxide was observed just below the external oxide scale and was distributed on the grain boundaries. The internal oxide was confimed as Al₂O₃. The Cr-depleted zone and internal oxide in both environments became thicker as the exposure time increased. The Cr₂O₃ in air at 2000 h was thinned in terms of its scale by CrO₃ evaporation and delamination. The Cr₂O₃ in He was constantly maintained.     

Cu-Ti合金在模拟S2-污染海水中的腐蚀行为研究

通过浸泡实验与电化学测试,研究了固溶态Cu-4wt.%Ti合金在模拟污染海水(含S2-的3.5wt.% NaCl溶液)的腐蚀行为。借助扫描电子显微镜(SEM)、X射线衍射(XRD)以及X射线光电子能谱仪(XPS)对铜钛合金表面腐蚀产物进行测试分析。结果表明：含Cl-溶液中铜钛合金的腐蚀形式为点蚀,点蚀坑尺寸较小,分布均匀。添加S2-后点蚀更容易被诱发,点蚀坑尺寸较大。当NaCl溶液中的S2-浓度达到60ppm时,点蚀坑在合金表面相互连接,呈现出均匀腐蚀的形态;S2-<和Cl-对铜钛合金的腐蚀存在竞争吸附,S2-吸附性强对铜钛合金的腐蚀剧烈;在含S2-的NaCl溶液中腐蚀产物主要为CuS、Cu2S、Cu2O以及Cu2(OH)3Cl。S2-浓度较大时会导致溶液中OH-浓度增加,使腐蚀产物膜层厚度与致密度增加,因此当S2-浓度达到100ppm时铜钛合金能够发生钝化从而减缓腐蚀。     

A wet ball milling treatment of Zr-based AB2 alloys as negative electrode materials

A wet ball milling fluorination treatment was successfully developed to improve rate discharge capabilities of Zr-based AB₂ alloys. In this work, treatment conditions such as constituents in the treating solution, ball milling speed and time were optimized. It was found that the Ni-rich surface layer formed through the Ni²⁺ reduction by alloy component elements played an important role in the initial activation property. The size of alloy powder particles can be easily adjusted by changing the ball milling speed and time. Although a small size of alloy powder particle is beneficial for quick kinetics, excessive pulverization resulted in a decreased capacity at low discharge rates.     

Corrosion behavior of an Al-6Mg-Sc-Zr alloy

The corrosion behavior of an Al-6Mg-Sc-Zr alloy was studied and compared with that of an Al-6Mg-Zr alloy. The addition of scandium into the Al-6Mg-Zr alloy reduced the susceptibility to exfoliation corrosion. By using the constant load tensile method in a 3.5 wt.% NaCl solution, the resistance to SCC of the Al-6Mg-Sc-Zr alloy was higher than that of the Al-6Mg-Zr alloy. When the specimens were not applied with an anodic current, the Al-6Mg-Sc-Zr alloy was resistance to SCC and no brittle cracking was found on the fracture surface. When an anodic current was applied, the Al-6Mg-Sc-Zr alloy specimens failed as a result of accelerated corrosion rather than SCC. It was believed that the addition of scandium re- sulted in （Al3Sc, Zr） particles that greatly refined grains and promoted the formation of homogeneous discontinuous distribution of β-phase in the alloy base, which much contributed to good corrosion resistance of the Al-6Mg-Sc-Zr alloy.     

LC4铝合金剥蚀及其电化学阻抗行为

研究了LC4铝合金双级过时效处理板材在EXCO剥蚀溶液中的剥蚀行为及其相应的电化学阻抗谱。结果表明 ,腐蚀由晶界孔蚀发展为沿平行于表面的晶界腐蚀 ,并在晶界堆积大体积的楔形腐蚀产物 ,挤压表层晶粒而导致剥蚀。由于双级过时效处理使强化相 η均匀析出 ,降低了合金的晶间腐蚀程度 ,导致合金剥蚀程度很轻 ,主要表现为局部小面积的金属表层鼓泡剥蚀。剥蚀后 ,电化学阻抗谱由两个容抗弧组成 ,其中高频容抗弧源于合金原表面 ,而中低频容抗弧源于剥蚀后露出并与腐蚀介质接触的新界面。有可能根据这两个容抗成分的分析来定量判断合金的剥蚀程度。     

Ni-Cu-P化学沉积镀层初期冲刷腐蚀的电化学行为

利用化学镀技术,采用碱性镀液配方,在紫铜基体上制备Ni-Cu-P三元合金镀层.经EDX分析镀层中Ni、Cu和P的含量约为78.9wt％、11.4wt％和9.7wt％,属于高磷镀层.经TEM分析镀层为混晶态结构.采用管式冲刷腐蚀试验机,利用电化学测试手段,综合宏观腐蚀形貌研究镀层初期冲刷腐蚀行为.探讨在人工海水中不同冲刷流速条件下,24 h的冲刷时间内,镀层反应的电化学阻抗谱信息.结果表明,不同冲刷流速对镀层耐蚀性能有明显的影响,冲刷条件相对于静态条件,镀层耐蚀性能明显下降,当冲刷流速为6.5 m/s时,镀层耐冲刷腐蚀性能相对于冲刷流速为3m/s、4m/s时,更加良好稳定.     

Corrosion behavior of pure Mg and AZ31 magnesium alloy

Protection of Metals and Physical Chemistry of Surfaces - Purpose of this article is to study corrosion behavior of pure magnesium and AZ31 magnesium alloy in electrolyte containing different...     

Corrosion behavior and surface characterization of tantalum implanted TiNi alloy

TiNi shape memory alloy has been modified by Ta plasma immersion ion implantation technology to improve corrosion resistance. The results of the polarization tests show that the corrosion resistance of TiNi alloy in Ringer's solution at 310 K has been improved by the Ta ion implantation and the Ta/TiNi sample with a moderate incident dose of 1.5 × 10¹⁷ ions/cm² exhibits the best corrosion resistance ability. The surface characterization and chemical composition of the Ta/TiNi samples were determined by Auger electron spectroscopy (AES), Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) methods. AFM images reveal that compact aggregates of nano-grains uniformly disperse on the surface of the Ta/TiNi samples. AES and XPS analyses on the Ta/TiNi sample show that the component of the surface layer is mainly composed of TiO₂ and Ta₂O₅, which is benefit to the corrosion resistance ability and biocompatibility.     

不同热处理态2024铝合金的腐蚀行为

分别在3.5%NaCl溶液、3.5%NaCl＋1.0%H2O2溶液和pH=12的3.5%NaCl溶液中进行动电位极化实验,研究2024 Al-Cu-Mg合金在不同热处理状态下的腐蚀行为。极化曲线表明,随着合金时效时间的延长,合金的腐蚀电位向负方向移动;向NaCl溶液中添加H2O2会使腐蚀电位正移;在pH=12的3.5%NaCl溶液中的极化曲线表现出明显的钝化现象。腐蚀试样表面表现为常见的腐蚀特征,但也有扩大的点蚀、晶间腐蚀现象出现。循环动电位极化曲线显示有宽的循环极化滞后环,不同的腐蚀模式表明合金的点蚀生长对合金的热处理状态敏感。通过显微组织分析,探讨了不同热处理状态下合金在不同NaCl溶液中的腐蚀机理。     

Corrosion behavior of Cu-Ni-Ag-Al alloy anodes in aluminium electrolysis

The behavior of Cu-Ni-Ag-Al alloy used as anode for aluminum electrolysis was directly visualized in a two-compartment see-through cell during electrolysis, and its performances were tested at 850℃ in acidic electrolyte molten salts consisting of 39.3%NaF-43.7%AlF3-8%NaCl-5?F2-4%Al2O3 for 40 h in a laboratory cell. The results show that nascent oxygen oxidizes the anodic surface to form oxide film at the beginning of electrolysis. X-ray diffraction analysis of alloy surface show that the oxide film on the anodic surface consists of CuO, NiO, Al2O3,CuAl2O4 and NiAl2O4. However, SEM image shows the oxide film is porous, loose and easy to fall into electrolyte and to contaminate aluminum. The corrosion mechanism of metal anodes was analyzed.     

2219铝合金搅拌摩擦焊接头腐蚀行为

采用晶间腐蚀试验和剥落腐蚀试验研究了2219铝合金搅拌摩擦焊接头的腐蚀行为,结合金相显微镜、扫描电镜及能谱仪等分析手段研究了接头腐蚀后的表面形貌和腐蚀产物的成分,并对接头腐蚀机理进行了初步的探讨.结果表明,搅拌摩擦焊焊核区耐蚀性比母材高;腐蚀从点蚀开始,逐渐发展为晶间腐蚀和剥落腐蚀的全面腐蚀形貌;接头组织成分的均匀化,降低了材料形成局部腐蚀原电池的倾向,使得电位正向移动,接头耐蚀性增强.     

Corrosion behavior of CuCrNiAl alloy in HCl solutions

1 Introduction Cu alloy has become a kind of important materials for ocean construction as its excellent anti-corrosion performance. Though this kind of alloy has been applied for a long time, it often undertakes serious corrosion, low strength and leakag…     

Corrosion behavior of LY11 aluminum alloy in soil

1lNTRODUCTIONAluminumanditsalloys,justlessthansteels,werewidelyusedincommunicati0nca-ble,pipelineandpowerstationandsooninsoil.Soilcorrosionexperimentsofvariousmaterialshavebeenconductedabroadsince1920,[1~3].Inourcountry,thenetworkofsoilcorrosionhavebeenbuiltsince195Os,steelandleadspecimenshavebeenburiedfr0mthen..[4'5],whilestain-lesssteelsandnonferrousmetalssince1989[6].Inthisexperiment,thecorrosionbehavi0rofLY1laluminumalloywasstudiedinneutralsoilofShenyang,Chengdu,acidsoilofShenzhen,Y…     

Corrosion electrochemical behavior of brass tubes in circulating cooling seawater

Electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) were used to study the corrosion electrochemical behavior of brass tubes in circulating cooling seawater using the developed sensor. EIS study shows that the inhibitor can lead to the formation of corrosion products on metal surface, which will then inhibit the corrosion process. When the flow rate of the seawater increases, the diffusion of oxygen speeds up and the action of filming on HA177-2 tube accelerates, resulting in decrease of corrosion rate. EN analysis shows that the flow rate of the seawater has little effect on pitting susceptivity of HSn70-1 tube; however the pitting susceptivity of HA177-2 tube increases with increasing flow rate. Good agreement is observed between the spectral noise resistance R30(f) calculated from EN data and the modulus of impedance. It is shown that the electrochemical noise technique can be used in corrosion monitoring.