共查询到20条相似文献,搜索用时 953 毫秒
1.
H. Nami A. Halvaee H. Adgi A. Hadian 《Journal of Materials Processing Technology》2010,210(10):1282-1289
Diffusion bonding of Al/Mg2Si metal matrix composite (MMC) using Cu interlayer at optimal bonding temperature of 540 °C for various bonding durations was investigated. This metal matrix composite (MMC) containing 15% Mg2Si particles was produced by in situ technique. Specific diffusion bonding process was introduced as a low vacuum technique. The composition and microstructure of the joined areas were examined by X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (EDS). Microhardness and shear tests were conducted to the samples to evaluate the effect of bonding duration on weldability. Several different diffusion layers exist at the bond region depending on the bonding duration. The shear strength of joints increased with bonding duration due to elimination of CuAl2 brittle diffusion layer. 相似文献
2.
Sónia Simões Filomena Viana Mustafa Koçak A. Sofia Ramos M. Teresa Vieira Manuel F. Vieira 《Journal of Materials Engineering and Performance》2012,21(5):678-682
In this article, the characterization of the interfacial structure of diffusion bonding a TiAl alloy is presented. The joining
surfaces were modified by Ni/Al reactive multilayer deposition as an alternative approach to conventional diffusion bonding.
TiAl substrates were coated with alternated Ni and Al nanolayers. The nanolayers were deposited by dc magnetron sputtering
with 14 nm of period (bilayer thickness). Joining experiments were performed at 900 °C for 30 and 60 min with a pressure of
5 MPa. Cross sections of the joints were prepared for characterization of their interfaces by scanning electron microscopy
(SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), high resolution TEM (HRTEM),
energy dispersive x-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Several intermetallic compounds form
at the interface, assuring the bonding of the TiAl. The interface can be divided into three distinct zones: zone 1 exhibits
elongated nanograins, very small equiaxed grains are observed in zone 2, while zone 3 has larger equiaxed grains. EBSD analysis
reveals that zone 1 corresponds to the intermetallic Al2NiTi and AlNiTi, and zones 2 and 3 to NiAl. 相似文献
3.
4.
Marzanna Ksiazek Maria Richert Aam Tchorz Lukasz Boron 《Journal of Materials Engineering and Performance》2012,21(5):690-695
There is a growing interest in metal-ceramic bonding for wide range of applications in electronic devices and high technology
industry for fabrication of metal matrix composites and bonding of ceramic components to metals. The object of the work was
to study the effect of Ti, Nb, and Ti + Nb thin films deposited by PVD method on alumina substrates on structure and bond
strength properties of Al/Al2O3 joints. The joints were fabricated using the results of a wetting experiment and the sessile drop method at a temperature
of 1223 K in a vacuum of 0.2 MPa for 30 min of contact. The structure of the metal/ceramic interface was investigated using
scanning electron microscopy. The elemental distribution at the metal-ceramic interface was analyzed using energy dispersive
x-ray spectroscopy. Transmission electron microscopy was also used to investigate some aspects of the metal/ceramic interface.
The bond strength properties of joints were measured using shear test. The shear strength results demonstrated significant
improvement of shear strength of Al/Al2O3 joints due to the application of Ti + Nb thin film on alumina substrate. Microstructural investigations of the interface
indicated that Al/coating/Al2O3 couples have diffusion transition interface which influences the strengthening of these joints. A conclusion could be drawn
that the presence of thin film layers changes the character of interaction and leads to the formation of new reaction products
in the bonding layer. 相似文献
5.
M. Joseph Fernandus T. Senthilkumar V. Balasubramanian S. Rajakumar 《Journal of Materials Engineering and Performance》2012,21(11):2303-2315
The main difficulty when joining magnesium (Mg) and aluminum (Al) alloys by fusion welding lies in the formation of oxide films and brittle intermetallic in the bond region which affects the integrity of the joints. However, diffusion bonding is a suitable process to join these two materials as no such characteristic defects are produced at the joints. The diffusion bonding process parameters such as bonding temperature, bonding pressure, holding time, and surface roughness of the specimen play a major role in determining the joint strength. In this investigation, an attempt was made to develop empirical relationships to predict the strengths of diffusion bonded AZ80 magnesium and AA6061 aluminum alloys dissimilar joints from the process parameters based on central composite factorial design. Response surface methodology was applied to optimize the process parameters to attain the maximum shear strength and bonding strength of the joint. From this investigation, it was found that the bonds produced with the temperature of 405.87?°C, pressure of 7.87?MPa, holding time of 29.02?min and surface roughness of 0.10???m exhibited maximum shear strength and bonding strength of 57.70 and 76.90?MPa, respectively. The intermetallic formation at the interface was identified. 相似文献
6.
Dissimilar joints of graphite and TZM alloys were obtained via vacuum diffusion bonding with a Zr interlayer. The influence of interfacial structure on the microstructure and mechanical properties of graphite/TZM alloy joints were investigated. The microstructure and compositions on the interface were observed and analyzed, and the tensile shear strength of the joints were evaluated. The interfacial morphologies showed good metallurgical combination with no apparent defects. A transition layer with a width of approximately 200 μm was formed. The interface products were squeezed into triangular grooves in the graphite, forming a serrated structure in the joint with a triangular groove structure. The microstructures in the transition layer were Mo2Zr, ZrC and solid solution. Some eutectic penetrated into the porous graphite pores of the adjacent graphite matrix, forming an island-like morphology. The welding mechanism was consistent with transient liquid phase bonding. The interfacial shear strength of the joint with a triangular groove structure could reach 38 MPa, which was higher than that of graphite. Fracture occurred partly in the graphite and partly in the transition layer. The serrated structure between the graphite and the transition layer effectively improved the bonding strength. 相似文献
7.
AbstractSolid state diffusion bonding of TiAl was carried out with different bonding parameters within the superplastic temperature range. The effect of post-bond heat treatment (PBHT) on the mechanical properties of the bonds was also studied. Defect free sound bonds were achieved within the temperature range 925–1150°C and the pressure range 20–40 MPa. Transverse microtensile specimens extracted from the bonds were tested to evaluate room temperature tensile properties of the bonds and to correlate them with bonding parameters. The bond strength increased with an increase in bonding temperature and pressure. All the specimens of the bond made at 925°C and 40 MPa, and most of the specimens of bonds made at 1000°C and 30 MPa and at 1100°C and 20 MPa, failed in the bond area; all the specimens of bonds made at 1100°C and 30 MPa and at 1150°C and 20 MPa failed in the base metal. Post-bond heat treatment at 1350°C for 1 h led to the transformation of the recrystallised γ grains at the bond inteface formed during bonding to a lamellar microstructure, resulting in an indiscernible bond line in all cases. This resulted in an improvement in the bond strength in most of cases. Moreover, the recrystallised γ grains were also formed away from the bond area in the bonds made at 1100°C and 30 MPa and at 1150°C and 20 MPa. After PBHT, these bonds exhibited slightly lower tensile strength values owing to the change in the base metal microstructure away from the bond area. 相似文献
8.
基于微细晶超塑性扩散连接方法,对TC4钛合金与1Cr18Ni9Ti不锈钢成功实现了直接扩散连接,系统分析了接头性能、界面微观结构及超塑性扩散连接机理。结果发现:TC4钛合金与1Cr18Ni9Ti奥氏体不锈钢直接超塑性扩散连接时,较佳连接工艺规范为:温度T=760~820 ℃,压力p=6~9 MPa,时间t=20~40 min;接头剪切强度τ=125.3~148.7 MPa。与一般直接扩散连接相比,连接温度降低了约100 ℃,接头的剪切强度提高了1倍以上,且连接试样无明显变形。细化热处理TC4钛合金与1Cr18Ni9Ti不锈钢超塑性扩散连接时,其接头的形成过程大致可分为3个阶段:形成紧密接触阶段、接触表面激活阶段及靠近活化中心的界面冶金结合区形成阶段。 相似文献
9.
The elevated temperature tensile experiments have been carried out on the magnesium alloy and results indicate that the magnesium alloy has excellent superplastic property.Gleebe-1500 testing machine was used in the diffusion bonding experiment on the superplastic magnesium alloy.Then,the shear stength of the joints under different conditions is obtained through shear testing and the optimum processing parameters for the diffusion bonding are achieved.By metallurgical microscope and scanning electron microscope (SEM),it is revealed that the micromechanism of diffusion bonding is the slide of grain boundaries caused by the growth of grains and atom diffusion of the superplastic magnesium alloy. 相似文献
10.
《Science & Technology of Welding & Joining》2013,18(5):405-411
AbstractIn the development of vehicle structures, the proper selection of adhesives to bond the steels is important for safety of operation. In this study, toughened epoxy was tested for the ability to bond steels developed for low temperature use. Lap shear bonded DP600 and DP780 steel joints were prepared and tested in open air at ambient temperature and inside an environmental chamber at ?40°C respectively using a split Hopkinson tensile bar machine. The impact properties of bulk adhesive at ?40°C were also measured. It was found that the exposure of joints to a ?40°C environment had little influence on impact strength and energy absorption. Scanning electron microscopy of fracture surfaces indicates differences in fracture paths and interfacial regions for the ?40°C exposed specimens. Changes in the interphase region caused by low temperature exposure may contribute to an increased susceptibility of the adhesive joint to bond degradation. 相似文献
11.
《Science & Technology of Welding & Joining》2013,18(5):268-272
AbstractTests have been carried out to assess the feasibility of diffusion bonding as a fabrication technology for vacuum tight joints in linear accelerator cells for the Next Linear Collider. High purity copper specimens were diffusion bonded over a range of temperatures from 400 to 1000°C, under high (3.45 MPa) and low (3.45 kPa) bonding pressures, and at two different diamond machined surface finishes. Experiments showed that diffusion bonds with strengths equal to, or greater than, that of silver brazed joints could be made at temperatures ≥700°C at the 3.45 MPa bonding pressure, or ≥800°C at the 3.45 kPa bonding pressure. Partial strength diffusion bonds were made at temperatures as low as 400°C at the high bonding pressure, whereas no bonding (zero strength) was observed at temperatures below 700°C at the low bonding pressure. Observations of the fracture surfaces of the diffusion bonded specimens showed that bonding begins by point asperity contact. At low bonding pressures, surfaces created by diamond turning of annealed copper specimens produce higher strength bonds than those created by diamond flycutting of unannealed surfaces, whereas at higher bonding pressures the effect of surface finish was less important. 相似文献
12.
采用有机溶剂保护实现了纯铝和纯镍的扩散连接。利用扫描电子显微镜、能谱分析以及X射线衍射等分析手段,确定了Al/Ni扩散连接接头典型的界面结构为Al/Al_3Ni_2/Ni。在扩散连接过程中利用有机溶剂防止铝表面发生二次氧化,相比直接扩散连接可得到更好的焊接质量。研究了连接温度对Al/Ni接头界面结构的影响规律,随着连接温度的升高各反应层厚度逐渐增加。当连接温度为490℃,连接时间为60 min,连接压力为2 MPa时,接头抗剪强度达到最大值,为17.83 MPa,比该工艺下直接扩散连接得到的焊接接头强度提高了约55%。 相似文献
13.
为改善砂轮磨削钢轨的性能,通过热压烧结再固化的方法制备超硬复合磨料树脂磨具试验样条,考察不同种类的复合磨料对样条抗弯强度、抗冲击强度及磨具磨耗比的影响,并用电镜观察磨削后磨具及钢轨对磨件的形貌,表征磨削表面质量.结果显示:超硬磨料与金属结合剂造粒后,抗弯强度、抗冲击强度、磨耗比均得到明显提高,最大分别提高50%、近2倍... 相似文献
14.
I. Demirci S. Mezghani A. Mkaddem M. El Mansori 《Journal of Materials Processing Technology》2010,210(3):466-473
This paper addresses the effects of bonds and grains of abrasive tools on the edge aspect of ground glass surface. Diamond grains and silicon carbide (SiC) grains combined with two bond types, i.e., resin and metal, were considered for this study. The surface edge characteristics were characterized using scanning electron microscope (SEM) and interferometer observations. In particular, the spectrum of arithmetic mean was investigated for distinguishing the different scales of analysis. Experimental results showed that the grinding forces vary sensitively with bond type and wheel velocity. Using diamond grains’ wheel, it was found that roughness level obtained with metallic bond is lower than that obtained with resin bond. However, using a resin-bonded wheel, two mechanisms of material removal were revealed according to grains’ type. (i) A partial ductile regime, i.e., ductile streaks and brittle fracture, obtained with diamond grains, and (ii) a fully ductile regime obtained with SiC grains. Thus, it was found that ground surface obtained using SiC grains’ wheel has a better roughness than that obtained using diamond grains wheel. Besides, SiC grains seem to lead to more marked streaks and form defects. 相似文献
15.
Bonding Mechanisms and Shear Properties of Alumina Ceramic/Stainless Steel Brazed Joint 总被引:1,自引:0,他引:1
G. W. Liu G. J. Qiao H. J. Wang J. P. Wang T. J. Lu 《Journal of Materials Engineering and Performance》2011,20(9):1563-1568
Al2O3 ceramic/stainless steel joints were fabricated by activated molybdenum-manganese (Mo-Mn) sintering metallization plus vacuum
brazing using Ag-28 wt.% Cu alloy. The bonding mechanisms including metallization and interfacial bonding were analyzed and
discussed by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD).
Tests were also carried out to examine the influence of brazing on joint shear strength. The metallization mechanisms of glassy
phase migration and chemical reaction were confirmed experimentally, while Ni coating was found to play a key role in the
joining of metallized ceramic to metal via the Ag-Cu filler layer. As a result of the joining, the average shear strength
of the joints exceeds 95 MPa, with the maximum reaching 110 MPa. 相似文献
16.
Marzanna Ksiazek Adam Tchorz Lukasz Boron 《Journal of Materials Engineering and Performance》2014,23(5):1635-1640
Al2O3/Al/Al2O3 joints were formed by liquid-state bonding of alumina substrates covered with a thin Ti + Nb coating of 900 nm thickness with the use of an Al interlayer of 30 μm at 973 K under a vacuum of 0.2 mPa for 5 min. The bond strength of the joints was examined by a four-point bending test at 295, 373, and 473 K. Optical, scanning, and transmission electron microscopies were applied for detailed characterization of the interface structure and failure characteristics of fractured joint surfaces. The analysis of the results has shown that (i) bonding occurred due to the formation of a reactive interface on the metal side of the joint in the presence of Al3Nb(Ti) precipitates and (ii) modification of Al2O3 by a thin layer of Ti + Nb increases the hardness at the interface and makes it possible to achieve reliable joints working at elevated temperatures. 相似文献
17.
利用两步法阳极键合技术成功实现了Al-glass-Al的连接,利用扫描电镜(SEM)观察Al-glass界面形貌,利用辉光放电发射光谱仪(GD-OES)分析界面元素(K,Na,O,Al)分布规律,利用原子力显微镜(AFM)分析键合前后玻璃的表面形貌,采用万能材料试验机测试了不同工艺参数下试样的力学性能.结果表明,第二次键合界面电流值明显高于第一次键合界面电流值;Al-glass-Al界面结合良好,玻璃两侧界面无明显差异;Al3+有向Na+耗尽层中扩散的趋势,先形成的耗尽层中Na+浓度明显高于后形成的耗尽层;键合过程中,Na+在玻璃表面析出,玻璃表面Ra升高,玻璃表面质量下降是造成玻璃试样沿第二次键合面Al (2)-glass界面断裂的主要原因. 相似文献
18.
Aluminum and magnesium were joined through diffusion bonding using Ni interlayer. The microstructure and mechanical performance of the Al/Ni/Mg joints at different temperatures was investigated by means of scanning electron microscope(SEM), electro-probe microanalyzer(EPMA), X-ray diffraction(XRD), Vickers hardness testing, and shear testing. The results show that the addition of Ni interlayer eliminates the formation of Mg–Al intermetallic compounds and improves the bonding strength of the Al/Mg joints. The Al/Ni/Mg joints are formed by the diffusion of Al, Ni and Mg, Ni. The microstructure at the joint interface from Al side to Mg side is Al substrate/Al–Ni reaction layer/Ni interlayer/Mg–Ni reaction layer/Mg substrate multilayer structure. The microhardness of the Mg–Ni reaction layer has the largest value of HV 255.0 owing to the existence of Mg_2Ni phase.With the increase of bonding temperature, the shear strength of the joints increases firstly and then decreases.The Al/Ni/Mg joint bonds at 713 K for 90 min, exhibiting the maximum shear strength of 20.5 MPa, which is greater than that of bonding joint bonded directly or with Ag interlayer. The fracture of the joints takes place at the Mg–Ni interface rather than the Al–Ni interface, and the fracture way of the joints is brittle fracture. 相似文献
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20.
根据原子扩散理论对MBl5超塑性镁合金进行了扩散连接工艺研究。扩散连接试验前采用三种不同方法去除MBl5镁合金表面的氧化膜,从中选出最佳方法。在Gleeble-1500型热/力模拟试验机上,对超塑性MBl5镁合金进行了在不同连接工艺条件下的扩散连接,在电子万能试验机上对扩散连接接头进行了剪切强度试验,从而获得了MBl5超塑性镁合金的最佳扩散连接工艺参数。利用金相显微镜、扫描电镜(SEM),对扩散连接接头微观组织进行分析,得出了MBl5超塑性镁合金主要是通过原子扩散和晶粒长大造成的原始焊接表面晶界的移动,促使接头表面原子充分扩散,形成牢固的连接。 相似文献