Recent progress in the research on magnesium and magnesium alloy foils:A short review

Magnesium and magnesium alloy foils have great potential for application in battery anodes,electromagnetic shielding,optics and acoustics,and biology because of their excellent specific damping,internal dissipation coefficients,magnetic and electrical conductivities,as well as high theoretical specific capacity.However,magnesium alloys exhibit poor deformation ability due to their hexagonal close-packed crystal structure.Preparing magnesium and magnesium alloy foils with thicknesses of less than 0.1 mm is difficult because of surface oxidation and grain growth at high temperatures or severe anisotropy after cold rolling that leads to cracks.Numerous methods have been applied to prepare magnesium alloy foils.They include warm rolling,cold rolling,accumulative roll bonding,electric plastic rolling,and on-line heating rolling.Defects of magnesium and magnesium alloy foils during preparation,such as edge cracks and breakage,are important factors for consideration.Herein,the current status of the research on magnesium and magnesium alloy foils is summarized from the aspects of foil preparation,defect control,performance characterization,and application prospects.The advantages and disadvantages of different preparation methods and defect(edge cracks and breakage)mechanisms in the preparation of foils are identified.

H_2 generation kinetics/thermodynamics and hydrolysis mechanism of high-performance La-doped Mg-Ni alloys in Na Cl solution——A large-scale and quick strategy to get hydrogen

In this work,La-doped Mg-Ni multiphase alloys were prepared by resistance melting furnace(RMF)and then modified by high-energy ball milling(HEBM).The hydrolysis H_(2) generation kinetics/thermodynamics of prepared alloys in Na Cl solutions have been investigated with the help of nonlinear and linear fitting by Avrami-Erofeev and Arrhenius equations.Combining the microstructure information before and after hydrolysis and thermodynamics fitting results,the hydrolysis H_(2) generation mechanism based on nucleation&growth has been elaborated.The final H_(2) generation capacities of 0La,5La,10La and 15 La alloys are 677,653,641 and 770 m L·g^(-1)H_(2) in 240 min at291 K,respectively.While,the final H_(2) generation capacities of HEBM 0La,5La,10La and 15 La alloys are 632,824,611 and 653 m L·g^(-1)H_(2) in 20 min at 291 K,respectively.The as-cast 15La alloy and HEMB 5La alloy present the best H_(2) production rates and final H_(2) production capacities,especially the HEBM 5La can rapidly achieve high H_(2) generation capacity(670 and 824 m L·g^(-1)H_(2) )at low temperature(291 K)within short time(5 and 20 min).The difference between the H_(2) generation capacities is mainly originated from the initial nucleation rate of Mg(OH)_(2) and the subsequent processes affected by the microstructures and phase compositions of the hydrolysis alloys.Relative low initial nucleation rate and fully growth of Mg(OH)_(2) nucleus are the premise of high H_(2) generation capacity due to the hydrolysis H_(2) generation process consisted by the nucleation,growth and contacting of Mg(OH)_(2) nucleus.To utilization H_(2) by designing solid state H_(2) generators using optimized Mg-based alloys is expected to be a feasible H_(2) generation strategy at the moment.

Three-dimensional modeling of effect of surface intermetallic phase on surface defects of Al-Fe-Si aluminum foils during twin-roll casting

Scanning electron microscopy and X-ray energy dispersive spectrum analysis show that the clusters of intermetallic AlFeSi particle are distributed on or near the aluminum foil stock surfaces heterogeneously. 3D finite element modeling shows that these clusters of hard particles induce the fracture of the nano-scale lubricant oil film at first and further lead to severe deformation in the nearby aluminum foil substrate along the rolling direction. Consequently, the optical property in this region differs from that in the surroundings, resulting in surface defects.

A novel method towards improving the hydrogen storage properties of hypoeutectic Mg-Ni alloy via ultrasonic treatment

Ultrasonic treatment has great contributions on modifying the morphology,dimension and distribution of constituent phases during solidification,which serve as dominate factors influencing the hydrogen storage performance of Mg-based alloys.In this research,ultrasonic treatment is utilized as a novel method to enhance the de-/hydriding properties of Mg-2Ni(at.%)alloy.Due to ultrasonic treatment,the microstructure of as-cast alloy is significantly refined and homogenized.Ascribing to the increased eutectic boundaries and shortened distance insideα-Mg for hydrogen atoms diffusion,the hydrogen uptake capacities and isothermal de-/hydriding rates improve effectively,especially at lower temperature.The peak desorption temperature reduces from 392.99°C to 345.56°C,and the dehydriding activation energy decreases from 101.93 k J mol^(-1)to 88.65 k J mol^(-1).Weakened hysteresis of plateau pressures and slightly optimized thermodynamics are determined from the pressure-composition isotherms.Owing to the refined primary Mg,a larger amount of hydrogen with the higher hydriding proportion is absorbed in the first stage when hydrides nucleate in eutectic region and grow on primary Mg periphery subsequently before MgH2colonies impinging,resulting in the enhancement of hydrogenation rates and capacities.

Response of structural and magnetic properties of ultra-thin FeCo–V foils to high-energy beam welding processes

Microstructural evolutions and grain-boundary-character distribution during high-energy-beam welding of ultra-thin Fe Co-V foils were studied. Detailed data about the boundaries, coincidence site lattice（CSL） relationships, grain sizes, and microstructural features were acquired from electron-backscatter diffraction（EBSD） maps. Moreover, the evolution of the magnetic properties during high-energy-beam welding was studied using vibrating sample magnetometry（VSM）. The fraction of low-angle boundaries was observed to increase in the fusion zones of both electron- and laser-beam-welded foils. The results showed that the fractions of low-Σ CSL boundaries（particularly twin boundaries, Σ3） in the fusion zones of the welded foils are higher than those in the base metal. Because the strain rates produced during high-energy-beam welding are very high（because of the extremely high cooling rate）, grain deformation by a slip mechanism is limited; therefore, deformation by grain twinning is dominant. VSM analysis showed that the magnetic properties of the welded foils, i.e., their remanence, coercive force, and energy product, changed significantly. The formation of large grains with preferred orientation parallel to the easy axis of magnetization was the main reason for the diminished magnetic properties.

Energy-storage welding connection characteristics of rapidly solidified Cu-Co alloy foils

The connection characteristics of rapidly solidified Cu-40%Co alloy foils were studied using a self-developed micro-type energy-storage welding machine. The results show that the microstructure of the alloy foils is characterized by uni form and fine equiaxed grains,whose maximum grain size is 1.8 μm. Under the o ptimum energy,the regular flat nugget is formed,low voltage and high capacitan ce are favorable for obtaining the perfect connection joints,whereas high volta ge and low capacitance are likely to result in the surface burn of the alloy foi ls. With the increase of welding energy,the spot welding joint will be transfor med from regular flat nugget to nugget-free one,and the microstructure tends t o coarsen. The welding parameters recommended are: welding voltage 80100 V,(electric) capacitance 1 8002 500 μF,and welding force 48 N.

Circumventing chemo-mechanical failure of Sn foil battery anode by grain refinement and elaborate porosity design

Tin (Sn) metal foil is a promising anode for next-generation high-energy–density lithium-ion batteries (LIBs) due to its high capacity and easy processibility. However, the pristine Sn foil anode suffers nonuniform alloying/dealloying reaction with lithium (Li) and huge volume variation, leading to electrode pulverization and inferior electrochemical performance. Herein, we proposed that reduced grain size and elaborate porosity design of Sn foil can circumvent the nonuniform alloy reaction and buffer the volume change during the lithiation/delithiation cycling. Experimentally, we designed a three-dimensional interconnected porous Sn (3DIP-Sn) foil by a facile chemical alloying/dealloying approach, which showed improved electrochemical performance. The enhanced structure stability of the as-fabricated 3DIP-Sn foil was verified by chemo-mechanical simulations and experimental investigation. As expected, the 3DIP-Sn foil anode revealed a long cycle lifespan of 4400 h at 0.5 mA cm^(−2) and 1 mAh cm^(−2) in Sn||Li half cells. A 3DIP-Sn||LiFePO_(4) full cell with LiFePO_(4) loading of 7.1 mg cm^(−2) exhibited stable cycling for 500 cycles with 80% capacity retention at 70 mA g^(−1). Pairing with high-loading commercial LiNi0.6Co0.2Mn0.2O_(2) (NCM622, 18.4 mg cm^(−2)) cathode, a 3DIP-Sn||NCM622 full cell delivered a high reversible capacity of 3.2 mAh cm^(−2). These results demonstrated the important role of regulating the uniform alloying/dealloying reaction and circumventing the localized strain/stress in improving the electrochemical performance of Sn foil anodes for advanced LIBs.

Preparation of Ni-Co Alloy Foils by Electrodeposition

Electrodeposition of Ni-Co alloy foils on titanium substrate was performed in an acid chloride- sulphate bath. The influences of electrodeposition parameters such as current density, temperature, pH value, cobalt sulphate and saccharin concentration on composition and current efficiency were investigated in detail. The morphology and the microstructure of deposits were analyzed by SEM and XRD, respectively. The results indicated that the optimum parameters were current density 3-4 A/dm2, pH 2-3, temperature 40-50?C, cobalt sulphate 20 g/l and saccharin 2-3 g/l. Chemical analysis of the deposits by EDS revealed anomalous Ni-Co codeposition occured in this system. The SEM showed that hydroxide particles were not present on the surface and that fine-grain, smooth and compact Ni-Co alloy deposits were obtained. The crystallographic structures of Ni-Co alloy foils were the fcc Ni solid solution. The Ni-Co alloy foils with Co content 17.3-37.2 wt% and thickness of 20-45 μm were bright with low residual stress and super toughness.

Morphology and Magnetic Properties of Electrodeposited Iron and Nickel Based Alloy Foils

An alternative to conventional process for the preparation of soft magnetic metal foils of Fe,Fe-Ni,Fe-Co and Fe-Ni-Co by electroforming was described.The microstructure and magnetic properties were observed.The results showed that the crystal size of the iron-based alloy foil is less than 10μm,while that of nickel-based alloy foil is about 2μm.Moreover,the electroformed Fe-Ni foil has better magnetic properties than the conventional milled permalloy 1J79 foil.

1235铝合金冷加工过程中组织演变

为进一步掌握铝箔坯料在冷加工过程中的组织演变规律,以1235铝合金双零箔坯料为研究对象,探究其7.0 mm厚铸轧坯料冷轧至3.8,1.8,0.9,0.5 mm过程中第二相形貌、尺寸的变化情况。结果表明,铸轧坯料冷轧一道次后均匀化退火未改变第二相的属性,只是在一定程度上改变了相的尺寸,组织内的θ相(FeAl_(3))会发生溶解和均匀化扩散,且在高温下部分θ析出相形貌发生了变化,长大变成针状;后在一道次冷轧至1.8 mm过程中针状相发生了明显的“折断”,但在随后的冷轧过程中,针状相被破碎至5~8μm范围内以后再很难被进一步破碎,验证了针状第二相“硬而脆”的特性,说明在退火过程中控制尺寸>5μm第二相的数量的重要性。

退火温度对GH3600合金箔材组织与性能的影响

目的探究退火温度对GH3600镍基高温合金箔材微观组织及力学性能的影响。为制备综合性能良好的GH3600箔材提供参考。方法将厚度为2 mm的铸态板材反复轧制退火得到组织均匀的0.3 mm厚度带材,再利用四辊冷轧机将带材轧制成厚度为0.1 mm和0.05 mm的箔材,然后将2种厚度箔材在950、1000、1050℃下保温1 h后空冷。通过金相观察、电子探针、EBSD检测及XRD分析来研究箔材的微观组织演变。通过拉伸实验检测箔材的室温拉伸性能。结果随着变形程度的增大,轧制态箔材晶粒沿轧制方向被拉长得更加明显。在相同热处理参数下,0.05 mm退火态箔材晶粒尺寸更小。退火后,箔材晶粒发生了回复再结晶并析出了细小的碳化物。随着退火温度的升高,晶内碳化物逐渐减少,孪晶界比例增大,再结晶程度及晶粒尺寸增大。0.05 mm箔材在1050℃退火时,其晶粒迅速粗化,在厚度方向上出现单层晶,导致箔材的抗拉强度及延伸率出现异常降低的现象,即“越小越弱”的尺寸效应。结论适宜的热处理工艺有助于改善箔材的微观组织,进而提高其力学性能。0.05 mm箔材在950℃下退火1 h时,其延伸率为19.1%,屈服强度以及抗拉强度分别达到293 MPa和560 MPa,综合力学性能良好。

附载体极薄铜箔中新型无机/有机复合剥离层的研究

[目的]剥离层是成功制备和应用附载体极薄铜箔的关键所在。针对目前单一无机或有机剥离层存在的问题,开展了无机-有机复合剥离层的研究,以期实现载体箔/剥离层/极薄铜箔的多界面剥离强度的差异化控制。[方法]首先电沉积制备了35μm厚的铜箔为载体箔,然后依次电沉积Zn-Ni合金层和浸镀2-巯基苯并咪唑(2-MBI)有机层,构建了无机/有机复合剥离层,最后在复合剥离层上电沉积极薄铜箔,制备出附载体极薄铜箔。[结果]Zn-Ni合金层浸镀于2-MBI中时,2-MBI分子可通过其N原子和S原子与Zn、Ni发生键合而锚定在合金层表面,进而构成Zn-Ni合金/2-MBI复合剥离层,令载体箔与极薄铜箔之间的剥离强度适中(约0.083N/mm),且两者剥离后极薄铜箔的光面无Zn-Ni合金残留。[结论]采用无机/有机复合剥离层可实现载体箔/剥离层/极薄铜箔多界面剥离强度的差异化控制,为成功制备附载体极薄铜箔奠定了基础。

铜-锌合金电沉积及脱合金化法制备多孔铜箔

[目的]纳米多孔铜由于其开放的多孔结构、较高的比表面积、较低的密度等独特的理化性能,在储能、催化剂、传感器等领域有巨大的应用潜力。为了解决金属锂作为锂离子电池负极材料时存在的锂枝晶及安全问题,采用脱合金化法制备多孔铜箔成为近年来的研究热点。[方法]先以钛板为基体电沉积铜箔基底,接着电沉积Cu-Zn合金,再脱合金化处理得到多孔铜箔。重点研究了工艺参数对Cu-Zn合金镀层形貌、结构和性能的影响。[结果]Cu-Zn合金电沉积的较优工艺条件为:电流密度1.0 A/dm^(2),温度40℃,时间20 min。该条件下所得Cu-Zn合金镀层表面平整、结构均匀、形成单一合金相,经脱合金化处理后Zn元素的去除率为70.6%。[结论]采用电沉积+脱合金化的方法有望制得孔径均匀的多孔铜箔,但会产生裂纹,有待进一步研究和改善。

Ni-Cu预合金爆炸箔电化学制备及电爆性能研究

为探究电爆等离子体引发合金反应的点火机理,进一步降低爆炸箔发火电压、提高能量利用率,采用电化学方法在铜爆炸箔表面原位可控沉积Ni-Cu预合金薄膜。进行了预合金爆炸箔微观形貌、成分构成和电爆特性等实验研究,结合电爆炸反应过程监测探究了电爆合金化反应路径和释能机理。研究结果表明:采用电化学恒电位方法沉积金属Cu和Ni,当应用电位分别为-0.2 V和-0.8 V,反应时间均为2 700 s时,沉积的Ni-Cu预合金材料呈5μm的立方体结构且分布均匀,无明显氧化物生成。所制备的Ni-Cu预合金爆炸箔在2 000 V充电电压下的能量利用率是Cu爆炸箔的2.11倍,在电爆发生50μs后可观察到明显的合金化反应发生,等离子体膨胀范围和火花持续时间均明显大于Cu爆炸箔,更有利于等离子体直接点火。

5056铝箔表面新型三价铬转化膜的形成过程及影响因素

目的提高5056铝箔的耐腐蚀性能,探究新型三价铬转化膜的形成过程和主要影响因素。方法在自主研发的新型三价铬转化液中对5056铝箔进行表面处理,通过改变镀膜时间、镀液pH、镀液温度来调控转化膜的结构和性能;通过重铬酸钾点滴测试、电化学测试、接触角测试、中性盐雾试验,对新型转化膜的耐腐蚀性能和表面特性进行表征;采用超薄切片辅助扫描电子显微镜、X射线光电子能谱、拉曼光谱对膜层的结构和成分进行分析。结果在优化工艺条件下,可在5056铝箔表面获得一层厚度约为80nm、具有较强疏水特性的化学转化膜,其主要成分为TiO_(2)、ZrO_(2)、Al2O_(3)、Cr(OH)_(3);经过三价铬转化膜处理后,在中性盐雾试验进行1632h后未观察到5056铝箔试样出现明显腐蚀迹象,也未发现三价铬向六价铬的转变。结论采用新型三价铬镀膜处理可以大幅提高5056铝箔在含NaCl环境中的耐腐蚀性能,随着镀膜时间的延长,合金表面先后经历转化膜的形核、稳定生长、开裂起皮、再生长与开裂起皮动态平衡等4个阶段,当转化膜稳定生长并完全覆盖合金表面时,其耐腐蚀性能最好。

GH3600合金箔材在航空发动机中长期服役后组织演化

以厚度0.05 mm的GH3600合金箔材制备的隔热层壳零件为研究对象,利用光学显微镜、扫描电镜及能谱分析等检测手段,探究了随航空发动机服役400 h后氧化程度差异较大的异常和正常隔热层壳零件的组织变化规律.结果表明:服役后,正常零件和异常零件的晶粒均发生了长大;正常零件中可观察到较多的M_(7)C_(3) 相,但数量少于初始固溶态,而异常零件的M_(7)C_(3) 相几乎完全溶解;异常零件表面氧化层较厚,为双层氧化物结构,较多晶界均已氧化开裂;正常零件氧化层较薄,为单层氧化物结构,仅在表面出现沿晶的裂纹.该研究结果表明,较长时间超温服役是异常隔热层壳零件产生的原因.

压延铜箔的无氰电镀镍铜黑化处理工艺

为了研究出相较于电镀纯镍黑化工艺成本更低的电镀镍铜黑化工艺,以NiSO_(4)·6H_(2)O、CuSO_(4)·5H_(2)O、H_(3)BO_(3)、(NH_(4))_(2)S_(2)O_(8)和C_(6)H_(15)NO_(3)为镀液基本成分,通过加入添加剂,使金属在铜箔表面沉积形成光陷阱结构,从而实现电镀镍铜使铜箔黑化的目的。研究了镀液成分及工艺参数对黑化箔镀层亮度的影响,对黑化箔镀层的成分进行了测试,并对黑化箔镀层结构进行了观察分析。研究结果表明:电镀镍铜的黑化箔镀层中Cu代替Ni形成镀层,黑化箔镀层成分为NiCu;通过加入添加剂可以使电镀时使用的电流密度降低,达到了降低成本的目的。

锑元素对Al-Fe合金的力学性能及耐蚀性的影响

锂离子电池铝塑膜用铝箔需要有较高的成形性及耐蚀性。通过场发射扫描电镜、万能拉伸试验机、电化学工作站等设备对不同Sb含量的Al-1.45Fe合金的力学性能及耐蚀性进行研究。研究结果表明:在Al-1.45Fe合金中添加适量的Sb,合金的伸长率升高;添加过量的Sb,合金的伸长率降低;当添加w(Sb)=0.05%时,合金的伸长率可以达到27.4%,与未添加Sb的合金的伸长率19.5%相比,提升了40.5%。极化曲线表明,添加Sb后,合金的自腐蚀电位升高,自腐蚀电流降低,耐蚀性得到提升。

Inconel718合金扩散连接接头的组织与性能研究

对细晶Inconel718高温合金无中间层和加Ni箔中间层两种情况下的扩散连接进行了研究,分析了不同的连接温度、连接压力、连接时间等工艺参数对接头剪切强度的影响;通过SEM、EPMA和金相技术对接头微观组织和力学性能进行了分析.确定了获得优质接头的最佳工艺参数区间,即扩散连接温度T=1050℃,连接压力P=20MPa,连接时间t=45min,选用Ni箔作为中间层,厚度为25μm.

3003铝合金箔制备过程中的组织演变

通过硬度、电阻测试,X射线衍射分析,以及光学显微镜、扫描电镜、透射电镜观察,研究了3003铝合金箔制备过程中的组织演变,探讨了Fe、Si杂质元素对3003铝合金组织及性能的影响。结果表明,随(Fe+Si)含量升高,Mn的固溶度降低,且αAl(Fe,Mn)Si相增多;3003铝合金冷轧后在300℃和500℃退火时有大量含Mn粒子析出,300℃退火时析出受到冷轧变形量的影响,而在500℃退火时的析出与冷轧变形量无关;此外,Fe/Si含量比高的3003铝合金箔可获得大量细小且均匀分布的第二相粒子。