在LiCl-KCl-CeCl_3熔盐中铝电极上欠电位沉积制备Al-Ce合金（英文）

在843 K LiCl-KCl-CeCl_3熔盐中活性铝电极上,研究了Ce(Ⅲ)离子的电化学行为和欠电位沉积Al-Ce合金。对比循环伏安曲线发现,在Al电极上Ce(Ⅲ)/Ce反应的氧化还原电势比在Mo惰性电极上更正;开路计时电位在金属铝和铈的沉积平台之间出现2个平台,这表明Ce(Ⅲ)在A1活性电极上可以生成两种金属间化合物。以上结果在电化学机理上说明Ce(Ⅲ)离子可以在Al电极上欠电位沉积形成金属间化合物。在该实验条件下通过恒电位电解,在Al电极上得到了Al-Ce合金,验证了电化学分析的结果。经XRD表征,证实形成了AlCe和AlCe_3两种合金,结合Al-Ce合金相图分析了只产生这两种合金的原因;结合开路电位计算了生成这两种合金的标准吉布斯自由能变值。经SEM和EDS表征,证明了铈在Al电极表面分布,并形成厚度均一约28μm的Al-Ce合金镀层。     

氯化物熔盐体系共电沉积法制备Al-Li-Gd合金的研究

在773K时,采用循环伏安法、方波伏安法和计时电位法研究了Gd(III)和Al(III)在LiCl-KCl-AlCl3-GdCl3熔盐体系中的电化学行为及共电沉积制备Al-Li-Gd合金,并借助XRD,SEM-EDS对所得合金进行表征.结果表明,Gd(III)在预先沉积的Al上欠电位沉积形成了两种Al-Gd金属间化合物,当电流密度超过-279.5 mA/cm2时,Al,Gd和Li能同时析出.通过调节熔盐中AlCl3的含量可以获得不同相的Al-Li-Gd合金.Al-Li-Gd合金含有Al2Gd和Al2Gd3,Gd在合金中分布不均匀,而Al的分布相对均匀.     

LiCl–KCl熔盐中共沉积直接电化学形成不同相Al–Y合金

本文在773K的LiCl–KCl–AlCl3–Y2O3熔盐体系中,采用循环伏安、方波伏安、开路计时电位和稳态极化研究了不同相的Al–Y合金的电化学制备过程。电化学研究表明钇在预先沉积的铝上欠电位沉积形成了两种铝钇金属间化合物。X-射线衍射研究表明：这两种Al–Y金属间化合物为Al2Y和α-Al3Y。通过金相显微镜和电子扫描显微镜对合金样品进行了表征,结果显示钇元素主要分布于块状析出物上。通过调节熔盐中AlCl3的含量可以获得不同相的Al–Y合金。     

LiCl-KCl熔盐中共沉积直接电化学形成不同相Al-Y合金（英文）

在773 K的LiCl-KCl-AlCl_3-Y_2O_3熔盐体系中,采用循环伏安、方波伏安、开路计时电位和稳态极化研究了不同相的Al-Y合金的电化学制备过程。电化学研究表明钇在预先沉积的铝上欠电位沉积形成了2种铝钇金属间化合物。X射线衍射研究表明:这2种Al-Y金属间化合物为Al_2Y和α-Al_3Y。通过金相显微镜和电子扫描显微镜对合金样品进行了表征,结果显示钇元素主要分布于块状析出物上。通过调节熔盐中AlCl_3的含量可以获得不同相的Al-Y合金。     

Reline低熔溶剂中铝纳米颗粒和叶状显微组织的电化学形核和长大:温度和工作电极角速度的影响

利用电化学和表面表征技术,研究在不同温度和工作电极角速度(ω)下,含Al(III)离子的Reline低共熔溶剂中铝在玻碳电极上形核和长大的电化学行为.结果表明,随着温度的升高,Al(III)DES的还原发生在较低的负电位,而此时伏安图中的电流峰增大,这对Al沉积动力学和热力学条件有利.实际上,由于Al被Al(OH)3(...     

在AlCl_3的辅助下从LiCl-KCl-AlCl_3-Nd_2O_3熔盐中电解提取Nd

研究了753 K时Nd在W和Al电极上Li Cl-KCl-AlCl_3-Nd_2O_3体系中的电化学行为,同时研究了AlCl_3对Nd_2O_3的氯化作用,并直接以Nd_2O_3为原料,在W和Al电极上电解提取Nd,获得Al-Nd合金.在W电极上,Li Cl-KCl-Nd_2O_3体系中的循环伏安曲线中并未观察到Nd还原的信号.加入AlCl_3后,观察到Nd在预先沉积Al基体上欠电位沉积形成3种Al-Nd金属间化合物的电化学信号.在Al电极上Li Cl-KCl-AlCl_3-Nd_2O_3体系中观察到2种Al-Nd金属间化合物的形成信号.测量结果表明,AlCl_3能有效地氯化Nd_2O_3.在-2 A下,W电极上恒电流电解提取Nd,获得了Al-Nd合金,XRD分析结果表明,形成的合金含Al2Nd相.而在活性Al阴极上电解提取Nd,获得的Al-Nd合金含Al3Nd相.     

NaCl-KCl-NdCl3-AlCl3熔盐体系电解制备Nd-Al合金及机理

在700℃的NaCl-KCl体系中,采用循环伏安法、方波伏安法和开路计时电位法等电化学测试方法研究了钨电极上Nd(Ⅲ)的电化学行为以及与Al(Ⅲ)共沉积的电化学过程。结果表明:在低扫描速率(0.1～0.5V·s~(-1))下,NaCl-KCl-NdCl_3熔盐中Nd(Ⅲ)的还原是一步交换3个电子的准可逆过程,该还原过程由扩散步骤控制,扩散系数约为1.2×10~(-5) cm~2·s~(-1)。将AlCl_3引入NaCl-KCl-NdCl_3熔体后,循环伏安、方波伏安以及开路计时电位测试结果表明,电解过程中形成了3种Nd-Al金属间化合物(Nd_3Al_(11)、NdAl_3和NdAl_2),其形成机理为Nd在预先沉积的Al上发生欠电位沉积。通过电动势法,计算了700℃时Nd-Al金属间化合物的热力学参数,如两相共存下Nd的活度和相对偏摩尔吉布斯自由能以及Nd-Al金属间化合物的标准吉布斯自由能。在-2.3 V下进行恒电位电解5 h制备了Nd-Al合金,所得合金由Nd_3Al_(11)、NdAl_3、NdAl_2和Al4种物相组成。     

利用ZrO2固体电解质研究Na3AlF6-SiO2熔盐中的电沉积

利用Y₂O₃稳定的Zr O₂固体电解质(YSZ)管集成构建Pt,O₂(air)|YSZ作为参比、辅助电极的三电极新型电化学池,在完全无碳和1323 K条件下采用Ir丝作工作电极对Na₃Al F₆-5%Si O₂(质量分数)熔盐体系进行循环伏安(CV)及恒电位电解测试,并结合热力学理论计算、SEM观察及EDS分析,研究了熔盐中有关金属在阴极上的析出电位及电沉积规律。结果表明,Si单质在Ir电极上可一步沉积得到,其在CV曲线上的峰电位在-1.65 V,而Al、Na (Zr)等合金化沉积电位负于-1.8 V,且沉积电位依次负向增大。在-1.8 V或-2.0 V电位下电解,还发现有Zr₅Si₄金属化合物颗粒生成,其生成电位在-1.7～-1.8 V之间。沉积的Si、Al、Na金属(合金)主要来源于Na₃Al F₆-Si O₂熔盐本身产生...     

AlCl_3-NaCl熔盐扩散增强纯镁耐腐蚀性的研究

对纯镁表面采用AlCl3-NaCl熔盐扩散处理,金相和SEM观察结果显示镁表面生成了厚度为10um左右的均匀合金层,XRD测试表明该合金层由单质镁和镁铝金属间化合物Mg17Al12、ε-MgAl、β-MgAl组成,用电极电位曲线、交流阻抗分析以及极化曲线比较熔盐扩散处理前后镁的耐腐蚀性能,结果显示熔盐扩散处理后镁的电极电位显著提高,腐蚀速率降低,较好地提高了镁的耐腐蚀性能.     

LiTFSi/KTf熔盐电解质中锂在铝电极上的电化学行为(英文)

采用循环伏安、计时电位和计时电流等电化学测试技术考察LiTFSI/KTf熔盐电解质中锂在铝电极上的电化学行为。结果表明:在该熔盐中,锂在铝电极上的电化学还原过程伴随着锂铝合金的成核过程,锂在铝电极上的嵌入过程平缓、稳定。恒电流充放电循环实验发现,首次循环的库仑效率很低,这主要归结于Li-Al合金对锂元素的持留能力。通过XRD和SEM表征了充放电前后铝电极的物相组成和表面形貌。计时电流实验发现,锂原子嵌入铝电极中形成α-Li-Al合金的过程受锂在铝基体内的扩散步骤控制,且该扩散系数为1.8×10-10cm2/s。     

Al-Zn-Ce合金的非晶形成能力及其晶化行为研究

本文采用X射线衍射及透射电镜测试方法研究了Al-Zn-Ce合金的非晶形成能力及其晶化行为。随着Ce含量的增加,Al2Zn2Ce和Al4Ce金属间化合物的出现,阻止了Al相和Zn相的相分离,有利于形成单一的非晶相,从而提高了合金的非晶形成能力。Al-Zn-Ce非晶合金的晶化存在相选择行为,Al2Zn2Ce和Al4Ce与fcc-Al相竞争形核生长,同时Al2Zn2Ce的形核生长优于Al4Ce,多种相的竞争形核和有限生长有利于Al-Zn-Ce非晶合金的形成。     

Ce含量对Mg-Li-Al-Zn合金显微组织和拉伸性能的影响(英文)

制备了Mg-5Li-3Al-2Zn-xCe(x=0-2.5;质量分数,%)铸态合金,并将所得合金分别于300°C和370°C进行均匀化和固溶处理;研究固溶处理后合金显微组织和拉伸性能的变化。结果表明,合金中加入Ce后出现Al2Ce/Al3Ce析出相,此时合金主要由α-Mg、Al2Ce、Al3Ce和AlLi相组成;固溶处理后合金中AlLi和Al-Ce析出相数量减少。析出相的数量与形态对合金的力学性能十分重要,含有1.0%Ce的合金获得了优良的拉伸性能。固溶处理后Mg-5Li-3Al-2Zn-0.5Ce合金的强度和伸长率都得到了大幅度的提高,这是因为合金在固溶处理后由于基体中的溶质原子增加而获得良好的固溶强化作用。     

Electrochemical deposition of aluminum on W electrode from AlCl_3-NaCl melts

Electrochemical deposition of aluminum on W electrode from AlCl3-NaCl melts was studied by cyclic voltammetry and chronopotentiometry. The results show that Al ( Ⅲ) is reduced in two consecutive steps, i.e., 4Al2Cl7-+3e-→Al+7AlCl4- and then AlCl4-+3e-→Al+4Cl-. The electrochemical reaction of 4Al2Cl7-+3e-→Al+7AlCl4- is reversible. Certain nucleation overpotential is required during the deposition of aluminum on W electrode. Chronopotentiometry analysis also shows that Al (Ⅲ ) is reduced in two consecutive steps under certain current density, which is in reasonable agreement with cyclic voltammograms. By using constant current deposition, the electrodeposits on Al substrate obtained at between 50 and 100 mA/cm2 are quite dense and well adherent to the Al substrate. The electrochemical deposition of aluminum on Cu substrate in AlCl3-NaCl melts indicates that the intermetallic compounds are formed. The intermetallic compounds are AlCu and Al2Cu.     

Effect of mischmetal and yttrium on microstructures and mechanical properties of Mg-Al alloy

The effect of yttrium and mischmetal(MMs)on the as-cast and solid solution treated structures of Mg-Al alloys with different Al-contents was investigated.The results show that the MMs in Mg-Al alloy existed in rod Al4(Ce,La)compound while Y in Mg-Al alloy in polygonal Al2Y compound.The amount of Mg17Al12 in Mg-Al alloy is decreased with increasing Y or MMs addition,and Mg17 Al12 intermetallic compound is changed from continuous network to discontinuous one.The Al4(Ce,La)and Al2Y compounds are not dissolved into Mg-Al alloy matrix during solid solution treatment so that their high heat stability can be exhibited.The experiment of mechanical properties indicate that elongation and impact toughness of the Mg-Al-Y alloy with polygonal Al2Y compound are higher than those of Mg-Al-MMs alloy with rod A4(Ce,La) compound.     

Electrochemical codeposition of typical α+β phases Mg-Li alloys from the molten LiCl-KCl-MgCl_2 system

Electrochemical codeposition of Mg-Li alloys on molybdenum electrodes was investigated in LiCl-KCl(50 wt.%:50 wt.%) melts containing different concentrations of MgCl2 at 973 K.Cyclic voltammograms show that the underpotential deposition of lithium on pre-deposited magnesium leads to the formation of liquid Mg-Li alloys.The deposition potentials of Mg(II) and Li(I) ions gradually near each other with MgCl2 concentration decreasing.Mg-Li alloys with typical α + β phases could be obtained by potentiostatic electrolysis from LiCl-KCl melts containing 5 wt.% MgCl2 at -2.25 V vs.Ag/AgCl(cathodic current density 1.70 A·cm-2) for 2.5 h.α phase, α + β phases, and β phase Mg-Li alloys with different lithium contents were obtained by potentiostatic electrolysis from LiCl-KCl melts with the different concentrations of MgCl2.The samples were characterized by X-ray diffraction and scanning electron microscopy.     

退火温度对Al(Ce)诱导Si薄膜晶化过程的影响研究

基于铝诱导晶化方法,通过直流磁控溅射离子镀技术利用纯Al、纯Si和Al(Ce)靶材,制备了Al-Si和Al(Ce)-Si薄膜.采用真空退火炉和X射线衍射仪在不同温度下,对样品进行了退火实验并分析了Al-Si和Al(Ce)-Si薄膜的晶化和生长过程;结合Si薄膜的生长机理,研究了Al和稀土Ce在对Si薄膜退火晶化过程中的...     

Interface reaction between SnAgCu/SnAgCuCe solders and Cu substrate subjected to thermal cycling and isothermal aging

Trace amount of rare earth Ce (0.03 wt.%) was added into SnAgCu solder in order to reform the properties of the solder. In this study, interface reaction mechanism during thermal cycling and isothermal aging, was studied by studying the formation and growth of the intermetallic compound (IMC) at the solder (SnAgCu or SnAgCuCe)/Cu interface, and the growth kinetics which forming IMC in both systems (SnAgCu or SnAgCuCe) were also investigated under different aging conditions. The results show that the morphology of IMCs formed both at SnAgCu/Cu and SnAgCuCe/Cu interfaces was gradually changed from scallop-like to planar-like, and the thickness of different IMCs evolved with the increasing of aging time. The results also indicate that the growth rate of IMC at both interfaces during thermal cycling was higher than that during isothermal aging. Especially, the addition of amount of rare earth Ce into the SnAgCu solder can refine the microstructures; decrease the thickness of the intermetallic compound layer of SnAgCu solder alloys.     

稀土Ce对Al-12Si合金微观组织影响

本文以Al、Al-Si、Al-Ce高纯组元配置一定质量百分比的Al-Si-Ce合金,采用多功能真空电弧熔炼炉YSU-ZZ进行熔炼,使用铜模吸铸法制备样品并对样品进行金相显微镜、扫描电镜(SEM)及能谱分析(EDS).重点研究了Ce的加入量及冷却速度等因素对共品硅的大小、形状和分布的影响.研究表明快速凝同可以很好的细化共...     

Recent Advances in Superplastic Intermetallics

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Electrochemical codeposition of typical α＋β phases Mg-Li alloys from the molten LiCl-KCl-MgC2 system

Electrochemical codeposition of Mg-Li alloys on molybdenum electrodes was investigated in LiCl-KCl (50 wt.%:50 wt.%) melts containing different concentrations of MgCl₂ at 973 K. Cyclic voltammograms show that the underpotential deposition of lithium on pre-deposited magnesium leads to the formation of liquid Mg-Li alloys. The deposition potentials of Mg(II) and Li(I) ions gradually near each other with MgCl₂ concentration decreasing. Mg-Li alloys with typical α + β phases could be obtained by potentiostatic electrolysis from LiCl-KCl melts containing 5 wt.% MgCl₂ at −2.25 V vs. Ag/AgCl (cathodic current density 1.70 A·cm⁻²) for 2.5 h. α phase, α + β phases, and β phase Mg-Li alloys with different lithium contents were obtained by potentiostatic electrolysis from LiCl-KCl melts with the different concentrations of MgCl₂. The samples were characterized by X-ray diffraction and scanning electron microscopy.