Interface structure of ultrasonic wedge bonding joints of Ni/Al

Nickel plated on a copper plate was selected as a bond surface for ultrasonic aluminum wedge bonds, and a series of experiments were carried out to study the microstructure characterization of the wedge bond interface. Bond lift-off characteristics were studied by using scanning electron microscopy （SEM） with EDS-test. Characteristics of input power of PZT transducer were analyzed by the driving electric signal measured with GDS-820 Digital Oscilloscope. The results show that the pattern of partially bonded material at the Ni-Al interface of ultrasonic wedge bonds exposed by peeling underdeveloped bonds simulates a ridged torus with an unbonded central and external region rubbed along pulse direction. Bond strength is located between the severely ridged torus and the non-adhering central and external area of the bond. For the same machine variables, ridge-peak and transforming ultrasonic energy of the first wedge bond are greater than that of the second wedge bond. For constant other machine variables, with the increasing load, the total area of bond pattern increases in size, and minor axis of torus extends major axis; with the increasing time, the ridged periphery spreads a whole torus, and the ridged location of the bonded region moves closer to the bond center; the sliding trace and the ridge-like of the bond pattern strengthen when more power is applied. Moreover, the machine variables have an optimal range for microstructure characteristics.     

Effect of trace rare earth element Er on Al-Zn-Mg alloy

1 Introduction Remarkable effects of rear-earth elements on aluminium alloys, such as eliminating impurities, purifying melt, refining as-cast structure, retarding recrystallization and refining precipitated phases, have been widely researched for a long…     

Surface behavior of pasted nickel electrodes with electrodeposited Co-Ce on substrate

1 Introduction MH/Ni batteries have supper specific energy density, better performance of charging and discharging, and are friendly to the surroundings. So, MH/Ni batteries have been applied widely in power tools[1]. The design of MH/Ni batteries is limi…     

Study on microstructure and properties of high velocity arc sprayed Fe3 Al intermetallic coating

Coating structural materials with Fe3Al based intermetallics may rapidly lend to industrial application of their environment and wear resistant features. In the present study, high velocity arc spraying (HVAS) was used to in-situ synthesize Fe3Al intermetallic coating. The microstructural characterization and properties of the coating have been investigated. The microstructure was found to consist of Fe3A1 based intermetallic ( 1303 and B2 ) and a-Fe regions together with fine oxide ( ct-Al2 03 ) layers. TEM images of coating show that the solidified lamellae are polycrystalline and have a grain size of the order of about 150 rim, and there also exists amorphous state in some areas. It can be concluded that a very high cooling rate has been obtained during HVAS process. Moreover, the coating has relatively higher ndhesion strength and microhardness, as well as lower density and porosity.     

Creep resistance of Mg-4 %Al-2 %RE-2 ? alloy

The creep resistance of the alloy Mg-4Al-2RE-2Ca（AEC422） and the base alloy AE42 was studied. The results reveal that the precipitated phases of AEC422 consist of Al2La and Al2Ca by contrast with the precipitated phase Al11La3 in AE42, which is instable and decomposes to A1l2La and Al at high temperature. Creep resistance of AEC422 is significantly improved compared with that of AE42. The microstructure of AEC422 has no obvious changes after creep test at 175℃ and 70MPa, as compared to that before creep test, indicating that Al2La and Al2Ca have high thermal stability. Especially Al2Ca phase largely increases the strength of the grain boundaries in AEC422, which accounts for the creep resistance improvement.     

Pseudo-semi-solid thixoforging of cup shell with Al/Al2O3

1 Introduction The composite has high strength and high hardness when some ductile metal is added into the ceramics, at the same time the fracture toughness can be improved availably[1?4]. We also know that the increase of toughness is because of the bri…     

Al2O3p/2024Al基复合材料的界面结构

利用TEM、HRTEM等分析测试手段,对挤压铸造法制备的Al2O3颗粒增强2024Al基复合材料的界面组织结构进行了观察与分析。结果表明：Al2O3p/2024Al基复合材料的界面结合良好,未发现界面反应物,铝基体与Al2O3颗粒以共格关系结合,界面属直接结合型,且Al2O3颗粒与Al基体存在如下的位向关系：Al2O3（1^-1^-21^-）//Al（1^-1^-1^-）;Al2O3〈3^-41^-1^-〉//Al〈110〉。     

热挤压工艺参数对挤压铸造SiCw/L3复合材料组织和性能的影响

研究了挤压比和挤压温度对挤压铸造ＳｉＣｗ／Ｌ３ 复合材料组织和性能的影响。结果表明,当挤压温度升高时, 晶须沿挤压方向定向排列程度基本未变, 而晶须的折断程度则减弱, 导致复合材料的抗拉强度提高; 当挤压比增大时, 晶须沿挤压方向定向排列程度增大, 晶须的折断程度也增大, 这两个决定强度的相反过程造成了复合材料的抗拉强度在挤压比为１８∶１ 时出现最大值。用修正的混合法则预测挤压态复合材料强度时, 必须增大基体对强度贡献部分的系数ｃ＊ 。     

Improvement of Strength in 2024 Al Alloy by Enhanced Solution Treatment

In present paper, the effect of enhanced solution on mechanical properties and aging behavior in a commercially available 2024A1 alloy were investigated using tension test and scanning electron microscopy. Differential scanning calorimeter (DSC) was used to measure the incipient melting behavior and then determine the technology parameter of enhanced solution heat treatment for high strength. The results show that an appropriately enhanced solution treatment can make final solution temperature higher than that of the conventional solution temperature and improves second phase solution without the formation of overheated microstructure. As the results, both the strength especially the yield strength and the resistance to over aging can be improved considerably without a large deterioration to tensile ductility.     

热循环对20%SiC_w/6061Al复合材料尺寸稳定性的影响

通过测量 2 0 % (体积分数 )SiCw/6 0 6 1Al复合材料热循环 (2 5℃→ 30 0℃→ 2 5℃ )后的尺寸变化 ,研究了复合材料的热循环尺寸稳定性。结果表明 ,复合材料尺寸稳定性直接与晶须的取向方式有关。如果晶须取向为混乱分布 ,热循环后复合材料的尺寸变化不明显。当晶须取向为定向排列时 ,热循环可造成复合材料沿晶须方向的尺寸增大 ,同时垂直晶须方向尺寸减小     

Effect of SiC volume fraction on the age-hardening behavior in SiC particulate-reinforced 6061 aluminum alloy composites

The age-hardening behavior in the SiC particulate-reinforced 6061 aluminum alloy composites (SiCp/6061 Al alloy composites) was investigated using hardness measurement, calorimetric technique and transmission electron microscopy. The aging time for the peak hardness in 10%SiCp/6061 Al and 20%SiCp/6061 Al alloy composites was shorter than that of the unreinforced 6061 Al alloy, and the age-hardening was most accelerated in the 20%SiCp/6061 Al alloy composite. It is induced from the high density of dislocations in SiCp/6061 Al alloy composites which act as heterogeneous nucleation sites of precipitates and as a high diffusivity path of alloy elements. The precipitation sequence and the aspect of precipitates in the 6061 Al alloy cannot be affected considerably by the presence of SiC particulate and the volume fraction of SiC particulate. The activation energies for the formation of the intermediate β' phase in the unreinforced 6061 Al alloy, 10%SiCp/6061 Al and 20%SiCp/6061 Al alloy composite were 142.6 kJ/mol, 127.3 kJ/mol, 106.1 kJ/mol, respectively.     

凝胶注模成型工艺制备SiCw/Al2O3陶瓷复合材料的性能研究

对SiC2/Al2O3陶瓷的低粘度、高固相体积分数浓悬浮体的制备以及凝胶注模成型后坯体的性能和显微结构进行了研究,着重分析了长径比不同的2种SiC晶须及其添加量对坯体性能的影响.结果表明,坯体的相对密度、抗弯强度与SiC晶须的长径比和添加量有关,浆料的粘度随着晶须长径比和添加量的增大而增加.坯体的抗弯强度随着晶须添加量的增加呈现一种先上升后下降的趋势.凝胶注模成型后坯体结构均匀、致密,相对密度为60%,抗弯曲强度达38.5 MPa.通过显微结构观察,裂纹偏转、晶须拔出和晶须桥连是晶须增强的主要机制.     

Effect of fabrication method on the aging behavior of 6061 Al matrix composites reinforced with SiC whiskers

Age hardening behaviors of SiC whisker reinforced composites with 6061 Al matrix fabricated by P.M. (powder metallurgy) and squeeze casting were investigated to examine the effect of the fabrication method on the aging kinetics. In the squeeze cast composite, numorous triangular particles which is believed to be MgAlp₂O₄ were observed at Al/SiC interfaces whereas no visible interface particles were observed in the P. M. composite. P.M. composite showed faster age hardening and reached the maximum hardness earler than the squeeze cast composites. The decrease of the aging kinetics in squeeze cast 6061 Al matrix composites compared to that in P.M. composites is thought to result from more severe depletion of Mg atoms due to interfacial reactions in squeeze cast composites. The uniformity of whisker distribution is suggested to influence the general aging behavior through its effect on the local dislocation density. Data on the aging kinetics and the interfacial reactions in other Al alloys were also examined to study various factors which can influence the aging kinetics.     

粒度组成对高体积分数SiC_p/Al复合材料性能的影响

采用凝胶注模法制备SiC预制件用于无压熔渗液态铝合金实现60～67 vol%SiCp/Al复合材料的近净成形制备,研究了碳化硅颗粒级配及热处理对复合材料力学和热学性能的影响.结果表明:不同粒度的SiC粉体在铝基体中分布均匀,无明显偏聚现象;采用较细的SiC颗粒级配和退火处理都能有效提高复合材料强度;粗颗粒级配能增大SiC在复合材料中的体积分数,有利于导热性能的提高和热膨胀系数的降低;SiCp/Al复合材料抗弯强度介于240～365 MPa,室温时热导率介于122～175 W·m-1·℃-1.之间,室温至250℃的平均线热膨胀系数小于7.5×10-6℃-1,满足电子封装的性能要求.     

SiC_p/Al电子封装材料与陶瓷元件浸渗连接机理研究

分别将陶瓷元件嵌入凝胶注模成型后的SiC预制型中,再采用气压浸渗T艺制备高体积分数SiCp/Al复合材料的同时,实现了复合材料与元件的原位连接.采用SEM、EDS和XRD等分析了连接界面的显微组织及界面反应,结果表明:SiCp/AI与元件间的界面反应产物由MgAl204和Mg3Al2(SiO4)3等组成,界面反应层厚度约2～3μm,产物生成量主要由Al合金中的Mg、元件中SiO2含量等因素决定;SiCp/Al复合材料与Al2O3元件通过气压浸渗可以实现有效的反应连接.     

SiCp/Al合金复合材料时效强化的综合模型

以颗粒强化和时效强化理论为基础，结合铝合金时效动力学研究了SiCp／Al合金复合材料中增强体尺寸、体积分数以及时效制度对屈服强度的影响．分析不同时效制度下复合材料屈服强度与时效参数的关系，建立了一个SiCp／Al合金复合材料的时效强化综合模型，利用该模型可以预测复合材料屈服强度随增强体体积分数和尺寸以及时效时间的变化规律，将模型应用于SiC颗粒增强2XXX铝合金复合材料，结果显示模型预测值与实验数据吻合很好．     

Deformation behavior of SiC particle reinforced Al matrix composites based on EMA model

Effects of the matrix properties,particle size distribution and interfacial matrix failure on the elastoplastic deformationbehavior in Al matrix composites reinforced by SiC particles with an average size of 5μm and volume fraction of 12%werequantitatively calculated by using the expanded effective assumption(EMA)model.The particle size distribution naturally bringsabout the variation of matrix properties and the interfacial matrix failure due to the presence of SiC particles.The theoretical resultscoincide well with those of the experiment.The current research indicates that the load transfer between matrix and reinforcements,grain refinement in matrix,and enhanced dislocation density originated from the thermal mismatch between SiC particles and Almatrix increase the flow stress of the composites,but the interfacial matrix failure is opposite.It also proves that the load transfer,grain refinement and dislocation strengthening are the main strengthening mechanisms,and the interfacial matrix failure and ductilefracture of matrix are the dominating fracture modes in the composites.The mechanical properties of the composites strongly dependon the metal matrix.     

Microstructure and damping behavior of SiCp/Gr/2024Al metal matrix composites by squeeze casting technology

SiCp/Gr/2024Al metal matrix composites were processed by squeeze casting technology. The microstructure of composites was observed by SEM and TEM, and the effects of graphite particulates and SiC particulates on the damping behaviors of composites were also investigated. The results show that the microstructure of composites was dense and homogeneous, without any interfacial reactivity among reinforcement/matrix interfaces. Compared with the damping capacity of 2024Al, the damping capacity of composites was enhanced significantly by addition of SiC or graphite particulates. The main damping mechanisms of SiCo/Al composites were ascribed to the dislocation damping, and those of SiCo/Gr/2024Al were attributed to the intrinsic damping and interface damping.     

SiC颗粒增强体对铝基复合材料微弧氧化膜生长的影响

用微弧氧化方法在SiCp／2024铝基复合材料表面沉积出较厚的陶瓷膜，测定了陶瓷膜的生长曲线和相组成，提出了金属基复合材料微弧氧化膜生长模型．结果表明，微弧放电烧结作用下，膜层内SiCp增强体大部分已被熔化并氧化，只有少数残余的SiCp颗粒仍然保留在靠近界面的膜层内．SiCp增强体阻碍了微弧氧化膜的生长，但它并未破坏微弧氧化膜的完整性，这同铝基复合材料阳极氧化膜结构完全不同．     

SiCp/2024 Al复合材料阳极氧化膜的结构和耐蚀性

用动电位阳极极化和点滴法评估了17％SiCp／2024Al复合材料(MMC)硫酸阳极氧化膜的耐蚀性，用光学显徽镜、SEM和TEM对氧化膜的形貌和结构进行了观察，用EDXS分析了膜的组成，极化实验结果表明，复合材料的阳极氯化膜具有良好的耐NaCl溶液腐蚀的能力，其腐蚀速度较未处理的基体降低了2个数量级以上。SEM形貌表明，SiC颗粒对膜的生长有阻碍作用，低电流密度下形成的阳极氧化膜膜层较薄，结构致密，孔隙细小，腐蚀实验结果表明该膜层具有更高的耐蚀性，TEM显示，MMC阳极氧化膜的孔隙分布严重不均，在SiC颗粒周围的基体中，孔隙密度较大，孔隙间距较小，孔径也较大，最大可达50nm，这表明阳极氧化膜具有低抗蚀性的结构特征，EDXS分析表明SiC颗粒在阳极氧化过程中会被氧化。